Robotic Hand-Held Surgical Instrument Systems With A Visual Indicator And Methods Of Controlling The Same

ABSTRACT

A system is provided comprising a robotic instrument for use with a surgical tool. In some versions, the robotic instrument comprises a hand-held portion to be held by a user and a tool support movably coupled to the hand-held portion to support the surgical tool. A plurality of actuators operatively interconnect the tool support and the hand-held portion to move the tool support in three degrees of freedom relative to the hand-held portion. An optional constraint assembly may operatively interconnect the tool support and the hand-held portion to constrain movement of the tool support relative to the hand-held portion in three degrees of freedom. A visual indicator assists users in positioning hand-held portion of the instrument to maximize the useability of the system.

TECHNICAL FIELD

The present disclosure relates generally to surgical robotic hand-heldinstrument systems and methods of use.

BACKGROUND

Physical cutting guides are used to constrain surgical tools whenresecting tissue from a patient. In some cases, physical cutting guidesconstrain such surgical tools for the purpose of preparing joints toaccept replacement implants. The time required to position and secure aphysical cutting guide to the patient can represent a significantportion of the overall time required to perform a surgical procedure.

Navigation systems (also referred to as tracking systems) can be used toproperly align and secure jigs, as well as track a position and/ororientation of a surgical tool used to resect tissue from a patient.Tracking systems typically employ one or more trackers associated withthe tool and the tissue being resected. A display can then be viewed bya user to determine a current position of the tool relative to a desiredcut path of tissue to be removed. The display may be arranged in amanner that requires the user to look away from the tissue and surgicalsite to visualize the tool's progress. This can distract the user fromfocusing on the surgical site. Also, it may be difficult for the user toplace the tool in a desired manner.

Robotically assisted surgery typically relies on large robots withrobotic arms that can move in six degrees of freedom (DOF). These largerobots may be cumbersome to operate and maneuver in the operating room.

There is a need for systems and methods to address one or more of thesechallenges.

SUMMARY

One general aspect includes a hand-held robotic system for use with asurgical tool. The hand-held robotic system also includes an instrumentthat includes a hand-held portion to be held by a user and a toolsupport coupled to the hand-held portion. The tool support may include atool drive motor to drive motion of the surgical tool and an actuatorassembly operatively interconnecting the tool support and the hand-heldportion to move the tool support to move the surgical tool in aplurality of degrees of freedom relative to the hand-held portion. Theactuator assembly including a plurality of actuators. The system mayalso include a visual indicator to guide the user where to place thehand-held portion. The control system may be coupled to the plurality ofactuators and the visual indicator, the control system being configuredto determine a position and/or orientation of the hand-held portion in afirst degree of freedom in a known coordinate system. The control systemmay also determine a range of motion of the tool support in a seconddegree of freedom based on the position and/or orientation of thehand-held portion in the first degree of freedom. The control system mayalso determine a position and/or orientation of the hand-held portion inthe second degree of freedom in the known coordinate system. The controlsystem may also control the visual indicator based on the positionand/or orientation of the hand-held portion and the range of motion inthe second degree of freedom.

Another general aspect includes a hand-held robotic system for use witha surgical tool. The hand-held robotic system also includes aninstrument that includes a hand-held portion to be held by a user and atool support coupled to the hand-held portion. The tool support mayinclude a tool drive motor to drive motion of the surgical tool. Theinstrument may also include an actuator assembly operativelyinterconnecting the tool support and the hand-held portion to move thetool support to move the tool in a plurality of degrees of freedomrelative to the hand-held portion, the actuator assembly including aplurality of actuators. The hand-held robotic system may also include avisual indicator to guide the user where to place the hand-held portion.The system may further include a control system coupled to the pluralityof actuators and the visual indicator. The control system may beconfigured to determine a first pose of the hand-held portion in a knowncoordinate system. The control system may also be configured todetermine a first range of motion in a first degree of freedom based onthe first pose and determine a second pose of the hand-held portion inthe known coordinate system. The control system may also determine asecond range of motion in the first degree of freedom based on thesecond pose, where the first and second range of motion are differentand the first and second poses are different. The control system mayalso determine a first position and/or orientation of the hand-heldportion based on the first pose in the first degree of freedom andcontrol the visual indicator based on the first position and/ororientation and the first range of motion, and determine a secondposition and/or orientation of the hand-held portion based on the secondpose in the first degree of freedom and control the visual indicatorbased on second position and/or orientation and the second range ofmotion.

Another general aspect is a method of controlling a visual indicator ofa hand-held robotic system for use with a saw blade. The robotic systemmay include a hand-held instrument having a hand-held portion to be heldby a user and a blade support movably coupled to the hand-held portionto support the saw blade. The hand-held instrument may include anactuator assembly operatively interconnecting the blade support and thehand-held portion. The actuator assembly may include a plurality ofactuators. The blade support may include a saw drive motor. The methodmay comprise the steps of determining a position and/or orientation ofthe hand-held portion in a first degree of freedom in a known coordinatesystem; determining a range of motion of the tool support in a seconddegree of freedom based on the position and/or orientation of thehand-held portion in the first degree of freedom in the known coordinatesystem. The method may also include determining a position and/ororientation of the hand-held portion in the second degree of freedom inthe known coordinate system. The method may include controlling thevisual indicator based on the position and/or orientation of thehand-held portion and the range of motion in the second degree offreedom.

Another general aspect is a hand-held robotic system for use with atool. The system may include an instrument that features a hand-heldportion to be held by a user and a tool support coupled to the hand-heldportion. The tool support may include a tool drive motor to drive motionof the tool. The instrument may include an actuator assembly operativelyinterconnecting the tool support and the hand-held portion to move thetool support to move the tool in a plurality of degrees of freedomrelative to the hand-held portion to align the tool. The actuatorassembly including a plurality of actuators. The system may include avisual indicator to guide the user where to place the hand-held portion.The system may include a control system coupled to the plurality ofactuators. The control system may be configured to determine a positionand/or orientation of the hand-held portion in a first degree of freedomand a second degree of freedom in a known coordinate system. The controlsystem may be configured to control the visual indicator based on theposition and/or orientation of the hand-held portion in the first andsecond degrees of freedom and a range of motion of the tool supportrelative to the hand-held portion in the first and second degrees offreedom. A method is similarly contemplated.

A BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present disclosure will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings.

FIG. 1 is a perspective view of a robotic system.

FIG. 2 is a perspective view of a robotic instrument being used to cutfive planes on a femur to receive a total knee implant.

FIGS. 3A-3C are illustrations of various pitch orientations of therobotic instrument.

FIGS. 4A-4C are illustrations of various roll orientations of therobotic instrument.

FIGS. 5A-5C are illustrations of various z-axis translation positions ofthe robotic instrument.

FIG. 6 is a front perspective view of the robotic instrumentillustrating one particular pose of a tool support relative to ahand-held portion.

FIG. 7 is a block diagram of a control system, and also illustratesvarious software modules.

FIG. 8 is a rear perspective view of the robotic instrument.

FIG. 9 is a side exploded view of the robotic instrument. FIG. 10 is aschematic view of various transforms of the hand-held robotic surgicalsystem.

FIG. 11 a partial cross-sectional view of the robotic instrument

FIG. 12 illustrates a Cartesian model of a workspace of the roboticinstrument.

FIG. 13 illustrates a first two-dimensional slice region with a firstrange of motion vector.

FIG. 14 illustrates the two-dimensional slice region of FIG. 13 , with afirst actual deviation vector.

FIG. 15 illustrates the two-dimensional slice region of FIG. 13 , with asecond range of motion vector.

FIG. 16 illustrates the two-dimensional slice region of FIG. 15 , with asecond actual deviation vector.

FIG. 17 illustrates the two-dimensional slice region of FIG. 16 , with athird actual deviation vector.

FIG. 18 illustrates the two-dimensional slice region of FIG. 13 , with athird range of motion vector and a different origin.

FIG. 19 illustrates a second two-dimensional slice region with a fourthrange of motion vector.

FIG. 20 illustrates the two-dimensional slice region of FIG. 19 with afourth actual deviation vector.

FIG. 21 illustrates a display screen with an elevation indicia.

FIG. 22 illustrates a display screen with a roll indicia.

FIG. 23 illustrates three display screens with a pitch-roll indicia inthree different configurations.

FIG. 24 illustrates a display screen with a pitch-roll indicia.

FIG. 25 illustrates a schematic representation of a visual indicatorincluding a light array.

FIG. 26 illustrates a display screen including a roll indicia, apitch-roll indicia and an elevation indicia when the instrument is in ahome position.

FIG. 27A illustrates a hand-held surgical instrument in a first spatialconfiguration other than a home position, with a display screen visualindicator.

FIG. 27B illustrates a hand-held surgical instrument in a second spatialconfiguration other than a home position, with a display screen visualindicator.

FIG. 27C illustrates a hand-held surgical instrument in a third spatialconfiguration other than a home position, with a display screen visualindicator.

FIG. 28 illustrates a hand-held surgical instrument in a first spatialconfiguration with a visual indicator including a plurality of lightsources.

FIG. 29A-29G show the visual indicator of FIG. 28 in different statespertaining to different spatial configurations of the hand-held surgicalinstrument.

FIG. 30A-30E show a schematic view of the translation visual indicatorof FIG. 28 in different states pertaining to different elevationconfigurations of the hand-held surgical instrument.

FIG. 31 shows another visual indicator configuration with a plurality oflight sources.

FIGS. 32A-C shows three exemplary display screen visual indicators tofacilitate positioning of a user's hand.

FIG. 33A show another exemplary visual indicator with a plurality oflight sources.

FIG. 33B show another exemplary visual indicator on a display screen.

FIG. 34 shows another exemplary visual indicator with a plurality oflight sources arranged in posts.

FIG. 35A-C show yet another visual indicator on a display screencorresponding to three different spatial configurations of the hand-heldsurgical instrument.

FIG. 36A-C show another visual indicator in three differentconfigurations.

FIG. 37 show another visual indicator including a plurality of lightsources.

FIG. 38 show a visual indicator that is implemented mechanically.

FIG. 39 show another visual indicator that is implemented mechanically.

FIG. 40 shows yet another visual indicator that is implementedmechanically.

FIG. 41 shows yet another visual indicator that is implementedmechanically.

FIGS. 42A-42C shows three more exemplary visual indicators.

DETAILED DESCRIPTION Overview

Referring to FIG. 1 , a robotic system 10 is illustrated. The roboticsystem 10 is shown performing a total knee procedure on a patient 12 toresect portions of a femur F and tibia T of the patient 12 so that thepatient 12 can receive a total knee implant IM. The robotic system 10may be used to perform other types of surgical procedures, includingprocedures that involve hard/soft tissue removal, or other forms oftreatment. For example, treatment may include cutting tissue,coagulating tissue, ablating tissue, stapling tissue, suturing tissue,or the like. In some examples, the surgical procedure involves kneesurgery, hip surgery, shoulder surgery, spine surgery, or ankle surgery,and may involve removing tissue to be replaced by surgical implants,such as knee implants, hip implants, shoulder implants, spine implants,or ankle implants. The robotic system 10 and techniques disclosed hereinmay be used to perform other procedures, surgical or non-surgical, andmay be used in industrial applications or other applications whererobotic systems are utilized.

Referring to FIGS. 1 and 2 , the robotic system 10 includes aninstrument 14. In some examples, a user manually holds and supports theinstrument 14 (as shown in FIG. 1 ). In some examples, the user maymanually hold the instrument 14 while the instrument is being at leastpartially, or fully, supported by an assistive device, such as a passivearm (e.g., linkage arm with locking joints, weight-balancing arm), anactive arm, or the like. As best shown in FIGS. 1 and 2 , the instrument14 comprises a hand-held portion 16 for being manually grasped, orsupported by the user, the assistive device, or both.

The instrument 14 may be freely moved and supported by a user withoutthe aid of a guide arm, e.g., configured to be held by a human userwhile effecting physical removal of material such that the weight of thetool is supported solely by a hand of the user during the procedure. Putanother way, the instrument 14 may be configured to be held such thatthe user's hand is supporting the instrument 14 against the force ofgravity. The instrument 14 may weigh 8 lbs. or less, 6 lbs. or less, 5lbs. or less, or even 3 lbs. or less. The instrument 14 may have aweight corresponding to ANSI/AAMI HE75:2009. The instrument 14 alsocomprises a tool support 18 for receiving a tool 20. In some examples,when the tool 20 is a saw blade 380, the tool support 18 may be referredto as a blade support. The method for operating the instrument 14 mayinclude a user suspending the weight of the instrument 14 without anyassistance from a passive arm or robotic arm. Alternately, the weight ofthe instrument 14 may be supported through use of a counter-balancedpassive arm, assistive device, or active robotic arm, such that the userdoes not have to support the entire weight of the instrument. In suchcases, the user may still grasp the hand-held portion 16 in order tointeract with or guide the instrument 14. The passive arm and thecontents of U.S. Pat. No. 9,060,794 to Kang et al. are incorporatedherein by reference. Furthermore, the robotic system 10, in someexamples, may be free from a robot arm having more than one joint inseries.

The tool 20 couples to the tool support 18 to interact with the anatomyin certain operations of the robotic system 10 described further below.The tool 20 may also be referred to as an end effector. The tool 20 maybe removable from the tool support 18 such that new tools or differenttools 20 can be attached when needed. The tool 20 may also bepermanently fixed to the tool support 18. The tool 20 may comprise anenergy applicator designed to contact the tissue of the patient 12. Insome examples, the tool 20 may be a saw blade, as shown in FIGS. 1 and 2, or other type of cutting accessory. In such instances, the toolsupport may be referred to as a blade support. It should be appreciatedthat in any instance where blade support is referred to, it may besubstituted for the term ‘tool support’ and vice-versa. However, othertools may be contemplated, such as the contents of U.S. Pat. No.9,707,043 to Bozung, which is hereby incorporated herein by reference.In some examples, the tool 20 may be a drill bit, an ultrasonicvibrating tip, a bur, a stapler, or the like. The tool 20 may comprisethe blade assembly and drive motor to cause oscillatory motion of theblade as shown in U.S. Pat. No. 9,820,753 to Walen et al. or U.S. Pat.No. 10,687,823, hereby incorporated herein by reference. Such drivingcomponents may comprise a transmission TM coupled to the drive motor Mto convert rotary motion from the drive motor M into oscillating motionof the tool 20.

The system and methods described in PCT/US2020/042128, entitled “RoboticHandheld Surgical Instrument Systems and Methods”, filed on Jul. 15,2020, are also hereby incorporated by reference.

An actuator assembly 400 comprising one or more actuators 21, 22, 23move the tool support 18 in three degrees of freedom relative to thehand-held portion 16 to provide robotic motion that assists in placingthe tool 20 at a desired position or orientation (e.g., at a desiredpose relative to the femur F, tibia T, or both during resection), whilethe user holds the hand-held portion 16. The actuator assembly 400 maycomprise actuators 21, 22, 23 that are arranged in parallel, in series,or a combination thereof. In some examples, the actuators 21, 22, 23move the tool support 18 in three or more degrees of freedom relative tothe hand-held portion 16. In some examples, the actuator assembly 400 isconfigured to move the tool support 18 relative to the hand-held portion16 in at least two degrees of freedom, such as pitch and z-axistranslation. In some examples, such as shown herein, the actuators 21,22, 23 move the tool support 18 and its associated tool supportcoordinate system TCS in only three degrees of freedom relative to thehand-held portion 16 and its associated base coordinate system BCS. Forexample, the tool support 18 and its tool support coordinate system TCSmay: rotate about its y-axis to provide pitch motion; rotate about itsx-axis to provide roll motion; and translate along an axis Z coincidentwith a z-axis of the base coordinate system BCS to provide z-axistranslation motion. The allowed motions in pitch, roll, and z-axistranslation are shown by arrows in FIG. 2 and in the schematicillustrations of FIGS. 3A-3C, 4A-4C, and 5A-5C, respectively. FIG. 6provides one example of a pose of the tool support 18 and a pose of thehand-held portion 16 within the range of motion of the instrument 14. Insome examples, not shown in the figures, actuators may move the toolsupport 18 in four or more degrees of freedom relative to the hand-heldportion 16.

Referring back to FIG. 2 , a constraint assembly 24 having a passivelinkage 26 may be used to constrain movement of the tool support 18relative to the hand-held portion 16 in the remaining three degrees offreedom. The constraint assembly 24 may comprise any suitable linkage(e.g., one or more links having any suitable shape or configuration) toconstrain motion as described herein. In the example shown in FIG. 2 ,the constraint assembly 24 operates to limit motion of the tool supportcoordinate system TCS by: constraining rotation about the z-axis of thebase coordinate system BCS to constrain yaw motion; constrainingtranslation in the x-axis direction of the base coordinate system BCS toconstrain x-axis translation; and constraining translation in the y-axisdirection of the base coordinate system BCS to constrain y-axistranslation. The actuators 21, 22, 23 and constraint assembly 24, incertain situations described further below, are controlled toeffectively mimic the function of a physical cutting guide, such as aphysical saw cutting guide.

Referring to FIG. 7 , the control system may include an instrumentcontroller 28, or other type of control unit, is provided to control theinstrument 14. The instrument controller 28 may comprise one or morecomputers, or any other suitable form of controller that directsoperation of the instrument 14 and motion of the tool support 18 (andtool 20) relative to the hand-held portion 16. The instrument controller28 may have a central processing unit (CPU) or other processors, memory,and storage (not shown). The instrument controller 28 is loaded withsoftware as described below. The processors could include one or moreprocessors to control operation of the instrument 14. The processors canbe any type of microprocessor, multi-processor, or multi-core processingsystem. The instrument controller 28 may additionally, or alternatively,comprise one or more microcontrollers, field programmable gate arrays,systems on a chip, discrete circuitry, or other suitable hardware,software, or firmware that is capable of carrying out the functionsdescribed herein. The term processor is not intended to limit anyembodiment to a single processor. The instrument 14 may also comprise auser interface UI with one or more displays or input devices (e.g.,triggers, push buttons, foot switches, keyboard, mouse, microphone(voice-activation), gesture control devices, touchscreens, etc.).

The control system 60 further includes one or more software programs andsoftware modules. The software modules may be part of the program orprograms that operate on the navigation controller 36, instrumentcontroller 28, or both, to process data to assist with control of therobotic system 10. The software programs or modules include computerreadable instructions stored in non-transitory memory 64 on thenavigation controller 36, instrument controller 28, or both, to beexecuted by one or more processors 70 of the instrument controller ornavigation controller 28, 36. The memory 64 may be any suitableconfiguration of memory, such as RAM, non-volatile memory, etc., and maybe implemented locally or from a remote server. Additionally, softwaremodules for prompting or communicating with the user may form part ofthe program or programs and may include instructions stored in memory 64on the navigation controller 36, instrument controller 28, or both. Theuser may interact with any of the input devices of the navigation userinterface UI or other user interface UI to communicate with the softwaremodules. The user interface software may run on a separate device fromthe navigation controller 36, or instrument controller 28.

The instrument controller 28 controls operation of the tool 20, such asby controlling power to the tool 20 (e.g., to the drive motor M of thetool 20 that controls cutting motion) and controlling movement of thetool support 18 relative to the hand-held portion 16 (e.g., bycontrolling the actuators 21, 22, 23). The instrument controller 28controls a state (e.g., position or orientation) of the tool support 18and the tool 20 with respect to the hand-held portion 16. The instrumentcontroller 28 can control velocity (linear or angular), acceleration, orother derivatives of motion of the tool 20 relative to the hand-heldportion 16 or relative to the anatomy that is caused by the actuators21, 22, 23. For implementations of the visual indicator where the visualindicator is coupled to the tool support or the hand-held portion, theinstrument controller may control the visual indicator. However, in somealternatives, a different processor within the control system maycontrol the visual indicator.

As shown in FIG. 2 , the instrument controller 28 may comprise a controlhousing 29 mounted to the tool support 18, or the hand-held portion 16or a combination thereof with one or more control boards 31 (e.g., oneor more printed circuit boards and associated electronic components)located inside the control housing 29. The control boards 31 maycomprise microcontrollers, field programmable gate arrays (FPGA),drivers, memory, sensors, or other electronic components for controllingthe actuators 21, 22, 23 and the drive motor M (e.g., via motorcontrollers). The instrument controller 28 may also comprise the controlconsole 33, which may be separate from the instrument, but in data andpower communication with the control boards 31. The sensors S, actuators21, 22, 23, or drive motor M described herein may feed signals to thecontrol boards 31, which transmit data signals out to the console 33 forprocessing, and the console 33 may feed control commands (e.g. currentcommands, torque commands, velocity commands, angle commands, positioncommands, or a combination thereof, as well as various control andconfiguration parameters) back to the control boards 31 in order topower and control the actuators 21, 22, 23 or the drive motor M. It iscontemplated that the processing may also be performed on the controlboard(s) of the control housing. In some examples, the processing of thecontrol algorithms may be distributed between the console and thecontrol housing. In one example, the position control and velocitycontrol calculations may be in the console and current control may be inthe field programmable gate arrays located in the control house. Ofcourse, it is contemplated that no separate control housing isnecessary, or the processing can be performed in any number of differentlocations.

In some versions, the console 33 may comprise a single console forpowering and controlling the actuators 21, 22, 23, and the drive motorM. In some versions, the console 33 may comprise one console forpowering and controlling the actuators 21, 22, 23 and a separate consolefor powering and controlling the drive motor M. One such console forpowering and controlling the drive motor M may be like that described inU.S. Pat. No. 7,422,582, filed on Sep. 30, 2004, entitled, “ControlConsole to which Powered Surgical Handpieces are Connected, the ConsoleConfigured to Simultaneously Energize more than one and less than all ofthe Handpieces,” hereby incorporated herein by reference. Flexiblecircuits FC, also known as flex circuits, may interconnect the actuators21, 22, 23 or other components with the instrument controller 28. Forexample, flexible circuits FC may be provided between the actuators 21,22, 23, and the control boards 31. Other forms of connections, wired orwireless, may additionally, or alternatively, be present betweencomponents.

Referring briefly back to FIG. 1 , the robotic system 10 furtherincludes a navigation system 32. One example of the navigation system 32is described in U.S. Pat. No. 9,008,757, filed on Sep. 24, 2013,entitled, “Navigation System Including Optical and Non-Optical Sensors,”hereby incorporated herein by reference. The navigation system 32 tracksmovement of various objects. Such objects include, for example, theinstrument 14, the tool 20 and the anatomy, e.g., the femur F and tibiaT. The navigation system 32 tracks these objects to gather stateinformation of each object with respect to a (navigation) localizercoordinate system LCLZ. As used herein, the state of an object includes,but is not limited to, data that defines the position, orientation, orboth, of the tracked object (e.g., coordinate systems thereof) orequivalents/derivatives of the position, orientation, or both. Forexample, the state may be a pose of the object, or may include linearvelocity data, angular velocity data, and the like.

The navigation system 32 may include a cart assembly 34 that houses anavigation controller 36 or other types of control units. A navigationuser interface UI is in operative communication with the navigationcontroller 36. The navigation user interface UI includes one or moredisplays 38. The navigation system 32 is capable of displaying graphicalrepresentations of the relative states of the tracked objects to theuser using the one or more displays 38. The navigation user interface UIfurther comprises one or more input devices to input information intothe navigation controller 36 or otherwise to select/control certainaspects of the navigation controller 36. Such input devices includeinteractive touchscreen displays. However, the input devices may includeany one or more of push buttons, pointer, foot switches, a keyboard, amouse, a microphone (voice-activation), gesture control devices, and thelike. In some examples, the user may use buttons located on the pointerto navigate through icons and menus of the user interfaces UI to makeselections, configuring the robotic system 10 or advancing through theworkflow. As mentioned below, any of the visual indicators that includedisplay screens may be displayed on the navigation user interface UI,such as on one or more of the displays 38.

The navigation system 32 also includes a localizer 44 coupled to thenavigation controller 36. In one example, the localizer 44 is an opticallocalizer and includes a camera unit 46. The camera unit 46 has an outercasing 48 that houses one or more optical sensors 50. The localizer 44may comprise its own localizer controller 49 and may further comprise avideo camera VC.

The navigation system 32 includes one or more trackers. In someexamples, the trackers include a pointer tracker PT, a tool tracker 52,a first patient tracker 54, and a second patient tracker 56. In theillustrated example of FIG. 1 , the tool tracker 52 is firmly attachedto the instrument 14, the first patient tracker 54 is firmly affixed tothe femur F of the patient 12, and the second patient tracker 56 isfirmly affixed to the tibia T of the patient 12. In this example, thepatient trackers 54, 56 are firmly affixed to sections of bone. Thetrackers 52, 54, 56 and pointer tracker are registered to theirrespective objects (e.g. bone, tool) and the navigation system 32manually, automatically, or a combination thereof. In some examples, thepointer tracker PT is firmly affixed to a pointer 57 and used forregistering the anatomy to one or more coordinate systems, including thelocalizer coordinate system LCLZ or used for other calibration andregistration functions. In one example, the pointer 57 may be used toregister the patient trackers 54, 56 to the bone which the tracker 54,56 is attached, respectively, and the tool tracker 52 (and optionally53) to the tool support 18, the tool 20, the hand-held portion 16, or acombination thereof. In some examples, the pointer tracker PT may beused to register the TCP of the instrument 14 to the tool tracker 52relative to a tracker coordinate system. This way, if the localizer 44is moved from position to position, the registration of the instrument14 is located relative to the tool tracker 52. However, other means ofregistration of the trackers 52, 54, 56 are contemplated and may beimplemented together or separately with the pointer tracker PT. Othertracker locations are also contemplated.

Throughout this description, various transforms are described, such as‘bone to tracker’ or ‘instrument TCP to tracker’, i.e., relative to the‘tracker coordinate system’ rather than to the camera coordinate system(C). The localizer coordinate system may be used as an intermediatecoordinate system during registration and bone prep, since all trackedobjects are measured with respect to C. During registration, ultimatelythe various localizer-referred poses are combined mathematically, andregistration results are stored ‘with respect to a tracker’, such thatif the camera (i.e., C) moves, the registration is still valid.

The tool tracker 52 may be affixed to any suitable component of theinstrument 14, and in some versions may be attached to the hand-heldportion 16, the tool support 18, directly to the tool 20, or acombination thereof. The trackers 52, 54, 56, PT may be fixed to theirrespective components in any suitable manner, such as by fasteners,clamps, or the like. For example, the trackers 52, 54, 56, PT may berigidly fixed, flexibly connected (optical fiber), or not physicallyconnected at all (ultrasound), as long as there is a suitable(supplemental) way to determine the relationship (measurement) of thatrespective tracker to the associated object. Any one or more of thetrackers 52, 54, 56, PT may include active markers 58. The activemarkers 58 may include light emitting diodes (LEDs). Alternatively, thetrackers 52, 54, 56, PT may have passive markers, such as reflectors,which reflect light emitted from the camera unit 46. Printed markers, orother suitable markers not specifically described herein, may also beutilized.

Various coordinate systems may be employed for purposes of tracking theobjects. For instance, the coordinate systems may comprise the localizercoordinate system C, the tool support coordinate system TCS, the basecoordinate system BCS, coordinate systems associated with each of thetrackers 52, 54, 56, PT, one or more coordinate systems associated withthe anatomy, one or more coordinate systems associated withpre-operative or intra-operative images (e.g., CT images, MRI images,etc.) or models (e.g., 2D or 3D models) of the anatomy — such as theimplant coordinate system, and a TCP (tool center point) coordinatesystem. In some examples, the robotic system 10 does not rely onpre-operative or intraoperative imaging to create the 2D or 3D models ofthe target bone. Rather, the robotic system may be used in an imagelesssystem using the pointer tracker PT to register the target anatomy,capturing various anatomical landmarks, which is then processed by thecontrol system 60 to morph a nominal bone model to match the captureddata In other examples, pre-operative and intraoperative imaging is usedto image the target area of the patient and then transform the 2D or 3Dimages into a 3D model of the target bone. It is also contemplated thatthe robotic system 10 may use a combination of imaged and imagelessprocedures in creating a 3D model of the target surgical area. Oneexemplary system is described in U.S. Pat. No. 8,617,174, which ishereby incorporated by reference. Coordinates in the various coordinatesystems may be transformed to other coordinate systems usingtransformations upon establishing relationships between the coordinatesystems, e.g., via registration, calibration, geometric relationships,measuring, etc.

As shown in FIG. 2 , in some examples, the TCP is a predeterminedreference point or origin of the TCP coordinate system defined at thedistal end of the tool 20. The geometry of the tool 20 may be definedrelative to the TCP coordinate system or relative to the tool supportcoordinate system TCS. The tool 20 may comprise one or more geometricfeatures, e.g., perimeter, circumference, radius, diameter, width,length, height, volume, area, surface/plane, range of motion envelope(along any one or more axes), etc. defined relative to the TCPcoordinate system or relative to the tool support coordinate system TCSand stored in the non-volatile memory of the control boards 31 in thecontrol housing 29 of the instrument 14, the navigation system 32, theinstrument controller 28, or a combination thereof. The tool centerpoint (TCP), in one example, is a predetermined reference point andcorresponding coordinate system defined at the tool 20. The TCP has aknown, or able to be calculated (i.e., not necessarily static), poserelative to other coordinate systems. The TCP coordinate system includesan origin point and a set of axes (e.g. x axis, y axis, z axis) whichdefine the pose of the TCP. By tracking the TCP (or knowing the pose ofthe TCP), the robotic system 10 may calculate the position andorientation of the instrument 14 based on the pose of the TCP and theknown positional relationship between the TCP and the features of theinstrument 14. In some examples, the tool 20 has a blade plane (e.g.,for saw blades) that will be described for convenience and ease ofillustration but is not intended to limit the tool 20 to any particularform. Points, other primitives, meshes, other 3D models, etc., can beused to virtually represent the tool 20. The origin point of the TCPcoordinate system may be located at the spherical center of the bur ofthe tool 20 or at the distal end of the saw blade 27 such that the TCPcoordinate system is tracked relative to the origin point on the distaltip of the tool 20. Alternatively, the TCP may be tracked using aplurality of tracked points. The TCP may be defined in various waysdepending on the configuration of the tool 20. The instrument may employthe joint/motor encoders, or any other non-encoder position sensingmethod, so the control system 60 may determine a pose or position of theTCP relative to the hand-held portion 16 and BCS. The tool support 18may use joint measurements to determine TCP pose or could employtechniques to measure TCP pose directly. The control of the tool 20 isnot limited to a center point. For example, any suitable primitives,meshes, etc., can be used to represent the tool 20. It should beappreciated that the TCP may alternatively be defined as a point, asopposed to a coordinate system. The TCP coordinate system allowscalculate any required reference points or geometry aspects of the toolonce you have determined the pose of the saw blade or other tool.

The TCP coordinate system, the tool support coordinate system TCS, andthe coordinate system of the tool tracker 52 may be defined in variousways depending on the configuration of the tool 20. For example, thepointer 57 may be used with calibration divots CD in the tool support 18or in the tool 20 for: registering (calibrating) a pose of the toolsupport coordinate system TCS relative to the coordinate system of thetool tracker 52; determining a pose of the TCP coordinate systemrelative to the coordinate system of the tool tracker 52; or determininga pose of the TCP coordinate system relative to the tool supportcoordinate system TCS. Other techniques could be used to measure thepose of the TCP coordinate system directly, such as by attaching andfixing one or more additional trackers/markers directly to the tool 20.In some versions, trackers/markers may also be attached and fixed to thehand-held portion 16, the tool support 18, or both. In instances wherethe hand-held portion includes a tracker, the pose of the hand-heldportion relative to the localizer/camera coordinate system LCTZ may bemeasured directly. In still other alternatives, the TCP may be definedrelative to the tool tracker, using the intermediate tool supportcoordinate system TCS.

Since the tool support 18 is movable in multiple degrees of freedomrelative to the hand-held portion 16 via the actuators 21, 22, 23, theinstrument 14 may employ encoders, hall-effect sensors (with analog ordigital output), or any other position sensing method, to measure a poseof the TCP coordinate system or tool support coordinate system TCSrelative to the base coordinate system BCS. In one example, theinstrument 14 may use measurements from sensors that measure actuationof the actuators 21, 22, 23 to determine a pose of the TCP coordinatesystem or tool support coordinate system TCS relative to the basecoordinate system BCS, as described further below.

The localizer 44 monitors the trackers 52, 54, 56, PT (e.g., coordinatesystems thereof) to determine a state of each of the trackers 52, 54,56, PT, which correspond respectively to the state of the objectrespectively attached thereto. The localizer 44 may perform knowntechniques to determine the states of the trackers 52, 54, 56, PT, andassociated objects (such as the tool, the patient, the tool support, andthe hand-held portion). The localizer 44 provides the states of thetrackers 52, 54, 56, PT to the navigation controller 36. In someexamples, the navigation controller 36 determines and communicates thestates of the trackers 52, 54, 56, PT to the instrument controller 28.

The navigation controller 36 may comprise one or more computers, or anyother suitable form of controller. Navigation controller 36 has acentral processing unit (CPU) or other processors, memory, and storage(not shown). The processors can be any type of processor,microprocessor, or multi-processor system. The navigation controller 36is loaded with software. The software, for example, converts the signalsreceived from the localizer 44 into data representative of the positionor orientation of the objects being tracked. The navigation controller36 may additionally, or alternatively, comprise one or moremicrocontrollers, field programmable gate arrays, systems on a chip,discrete circuitry, or other suitable hardware, software, or firmwarethat is capable of carrying out the functions described herein. The termprocessor is not intended to limit any embodiment to a single processor.

Although one example of the navigation system 32 is shown to determineobject states, the navigation system 32 may have any other suitableconfiguration for tracking the instrument 14, tool 20, or the patient12. In another example, the navigation system 32 or localizer 44 areultrasound-based. For example, the navigation system 32 may comprise anultrasound imaging device coupled to the navigation controller 36. Theultrasound imaging device images any of the aforementioned objects,e.g., the instrument 14, the tool 20, or the patient 12, and generatesstate signals to the navigation controller 36 based on the ultrasoundimages. The ultrasound images may be 2D, 3D, or a combination of both.The navigation controller 36 may process the images in near real-time todetermine states of the objects. The ultrasound imaging device may haveany suitable configuration and may be different than the camera unit 46as shown in FIG. 1 .

In another example, the navigation system 32 or localizer 44 are radiofrequency (RF)-based. For example, the navigation system 32 may comprisean RF transceiver coupled to the navigation controller 36. Theinstrument 14, the tool 20, or the patient 12 may comprise RF emittersor transponders attached thereto. The RF emitters or transponders may bepassive or actively energized. The RF transceiver transmits an RFtracking signal and generates state signals to the navigation controller36 based on RF signals received from the RF emitters. The navigationcontroller 36 may analyze the received RF signals to associate relativestates thereto. The RF signals may be of any suitable frequency. The RFtransceiver may be positioned at any suitable location to track theobjects using RF signals effectively. Furthermore, the RF emitters ortransponders may have any suitable structural configuration that may bemuch different than the trackers 52, 54, 56, PT shown in FIG. 1 .

In yet another example, the navigation system 32 or localizer 44 areelectromagnetically based. For example, the navigation system 32 maycomprise an EM transceiver coupled to the navigation controller 36. Theinstrument 14, the tool 20, or the patient 12 may comprise EM componentsattached thereto, such as any suitable magnetic tracker,electro-magnetic tracker, inductive tracker, or the like. The trackersmay be passive or actively energized. The EM transceiver generates an EMfield and generates state signals to the navigation controller 36 basedupon EM signals received from the trackers. The navigation controller 36may analyze the received EM signals to associate relative statesthereto. Again, the navigation system 32 examples may have structuralconfigurations that are different than the navigation system 32configuration shown in FIG. 1 .

The navigation system 32 may have any other suitable components orstructure not specifically recited herein. Furthermore, any of thetechniques, methods, or components described above with respect to thenavigation system 32 shown may be implemented or provided for any of theother examples of the navigation system 32 described herein. Forexample, the navigation system 32 may utilize solely inertial trackingor any combination of tracking techniques, and may additionally oralternatively comprise, fiber optic-based tracking, machine-visiontracking, and the like.

Referring to FIG. 7 , the robotic system 10 includes a control system 60that comprises, among other components, the instrument controller 28 andthe navigation controller 36. The control system 60 further includes oneor more software programs and software modules. The software modules maybe part of the program or programs that operate on the instrumentcontroller 28, navigation controller 36, or a combination thereof, toprocess data to assist with control of the robotic system 10. Thesoftware programs or modules include computer readable instructionsstored in memory 64 on the instrument controller 28, navigationcontroller 36, or a combination thereof, to be executed by one or moreprocessors 70 of the instrument controllers 28. The memory 64 may be anysuitable configuration of memory, such as non-transitory memory, RAM,non-volatile memory, etc., and may be implemented locally or from aremote database. Additionally, software modules for prompting orcommunicating with the user may form part of the program or programs andmay include instructions stored in memory 64 on the instrumentcontroller 28, navigation controller 36, or a combination thereof. Theuser may interact with any of the input devices of the navigation userinterface UI or other user interface UI to communicate with the softwaremodules. The user interface software may run on a separate device fromthe instrument controller 28 or navigation controller 36. The instrument14 may communicate with the instrument controller 28 via a power, dataconnection, or both. The power connection, data connection, or both mayprovide a path for the input and output used to control the instrument14 based on the position and orientation data generated by thenavigation system 32 and transmitted to the instrument controller 28, asshown as the BUS/COMM connection 37 in FIG. 7 .

The control system 60 may comprise any suitable configuration of input,output, and processing devices suitable for carrying out the functionsand methods described herein. The control system 60 may comprise theinstrument controller 28, the navigation controller 36, or a combinationthereof, or may comprise only one of these controllers, or additionalcontrollers. The controllers may communicate via a wired bus orcommunication network as shown in one example as the BUS/COMM connection37 in FIG. 7 , via wireless communication, or otherwise. The controlsystem 60 may also be referred to as a controller. The control system 60may comprise one or more microcontrollers, field programmable gatearrays, systems on a chip, discrete circuitry, sensors, displays, userinterfaces, indicators, or other suitable hardware, software, orfirmware that is capable of carrying out the functions described herein.

Instrument

In one exemplary configuration, one exemplary instrument 14 is bestshown in FIGS. 8 and 9 . The instrument 14 includes the hand-heldportion 16 to be held by the user, the tool support 18 movably coupledto the hand-held portion 16 to support the tool 20, the actuatorassembly 400 with the plurality of actuators 21, 22, 23 operativelyinterconnecting the tool support 18 and the hand-held portion 16 to movethe tool support 18 in at least three degrees of freedom relative to thehand-held portion 16, and the constraint assembly 24 having the passivelinkage 26 operatively interconnecting the tool support 18 and thehand-held portion 16. While a particular robotic instrument is describedthroughout the figures, the visual indicators described herein may beused within any multiple degree of freedom robotic surgical instrument,including those that have different degrees of freedom that theinstrument 14.

The hand-held portion 16 often comprises a grip 72 for being grasped bythe user so that the user is able to manipulate, guide, or grasp theinstrument 14. The hand-held portion 16 may be configured with ergonomicfeatures such as a grip for a hand of a user to hold, a textured ormixed material coating for preventing a user's hand from slipping whenwet or bloody. The hand-held portion 16 may include a taper toaccommodate users with different hand sizes and contoured to mate withthe contours of a user's hand or fingers. The hand-held portion 16 alsocomprises a base 74 to which the grip 72 is attached by one or morefasteners, adhesive, welding, or the like. In the version shown, thebase 74 comprises a sleeve 76 having a generally hollow cylindricalshape. Joint supports 77, 78, 79 extend from the sleeve 76. Theactuators 21, 22, 23 may be movably coupled to the base 74 at the jointsupports 77, 78, 79 via joints described further below.

The tool support 18 comprises a tool support body 80 to which the tooltracker 52 can be fixed to or removably mounted via one or more trackermounts fixed to the tool support 18 at one or more mounting locations82. In one example, the tool tracker 52 is integrated with the toolsupport 18. In another example, the tool tracker 52 is removably mountedat the one or more mounting locations 82. The tool 20 is removablycoupled to the tool support 18 in the version shown. In particular, thetool support 18 comprises a tool coupler, such as head 84 to which thetool 20 is mounted, as described in U.S. Pat. No. 9,820,753 to Walen etal., incorporated herein by reference. The head 84 may be configured toutilize an oscillating-style of saw blade, as well as a sagittal-stylesaw blade or saw blade cartridge. The drive motor M that drivesoperation of the tool 20 is disposed in the tool support body 80 (e.g.,to drive oscillation of the saw blade in some versions). The tool 20 maybe attached to and released from the head 84 in the manner disclosed inU.S. Pat. No. 9,820,753 to Walen et al., incorporated herein byreference. As best shown in FIG. 9 , the tool support 18 also comprisesa plurality of actuator mounts 86, 88, 90 at which the actuators 21, 22,23 are to be movably coupled to the tool support 18 via joints, asdescribed further below. The actuator mounts 86, 88, 90 may comprisebrackets, or the like, suitable to mount the actuators 21, 22, 23 suchthat the tool support 18 is able to move in at least three degrees offreedom relative to the hand-held portion 16.

The actuators 21, 22, 23, in the version shown, comprise electric,linear actuators that extend between the base 74 and the tool supportbody 80. When actuated, an effective length of the actuator 21, 22, 23changes to vary a distance between the tool support body 80 and the base74 along a corresponding axis of the actuator 21, 22, 23. Accordingly,the control system 60 commands the actuators 21, 22, 23 to work in acoordinated fashion, responding to individual inputs given to eachactuator 21, 22, 23, respectively, by the control system 60 to changetheir effective lengths and move the tool support 18 in at least threedegrees of freedom relative to the hand-held portion 16 into the targetpose. In the version shown, three actuators 21, 22, 23 are provided, andmay be referred to as first, second, and third actuators 21, 22, 23 orfront actuators 21, 22, and rear actuator 23. The first, second, andthird actuators 21, 22, 23 are adjustable in effective length along afirst active axis AA1, a second active axis AA2, and a third active axisAA3 (see FIG. 9 ). The first, second, and third actuators 21, 22, 23 areindependently adjustable in effective length to adjust one or more of apitch orientation, a roll orientation, and a z-axis translation positionof the tool support 18 relative to the hand-held portion 16, aspreviously described. More actuators may be provided in some examples.The actuators may comprise rotary actuators in some examples. Theactuators 21, 22, 23 may comprise linkages having one or more links ofany suitable size or shape. The actuators 21, 22, 23 may have anyconfiguration suitable to enable movement of the tool support 18relative to the hand-held portion 16 in at least three degrees offreedom. For example, in some versions, there may be one front actuatorand two rear actuators, or some other arrangement of actuators.

In this version, the actuators 21, 22, 23 are coupled to the base 74 andthe tool support body 80 via a plurality of active joints. The activejoints include a set of first active joints 92 that couple the actuators21, 22, 23 to the tool support body 80 at the actuator mounts 86, 88,90. In one version, as shown in FIG. 9 , the first active joints 92comprises active U-joints. The U-joints comprise first pivot pins 94 andjoint blocks 96. The first pivot pins 94 pivotally connect the jointblocks 96 to the actuator mounts 86, 88, 90 via throughbores 98 in thejoint blocks 96. Set screws 100 may secure the first pivot pins 94 tothe actuator mounts 86, 88, 90. The U-joints may also comprise secondpivot pins 104. The joint blocks 96 have crossbores 102 to receive thesecond pivot pins 104. The second pivot pins 104 have throughbores 103to receive the first pivot pins 94, such that the first pivot pins 94,the joint blocks 96, and the second pivot pins 104 form a cross of theU-joint. The first pivot pin 94 and the second pivot pin 104 of eachU-joint define pivot axes PA that intersect. The second pivot pins 104pivotally connect a pivot yoke 106 of the actuators 21, 22, 23 to thejoint blocks 96. As a result, the actuators 21, 22, 23 are able to movein two degrees of freedom relative to the tool support body 80. Othertypes of active joints are also contemplated, such as active sphericaljoints comprising balls with slots that receive pins.

Referring to FIG. 9 , the active joints also comprise a set of secondactive joints 108 coupling the front two actuators 21, 22 to the base 74of the hand-held portion 16. In the version shown, the second activejoints 108 are supported at the joint supports 77, 78. Each of thesecond active joints 108 comprises a swivel yoke 110 arranged to swivelrelative to the base 74 of the hand-held portion 16 about a swivel axisSA. Each swivel yoke 110 has a swivel head 112 and a post 114 extendingfrom the swivel head 112 to pivotally engage the base 74 at one of thejoint supports 77, 78. Nuts 115 threadably connect to one end of theposts 114 to trap the posts 114 in the base 74 while allowing therespective swivel yoke 110 to freely rotate within its respective jointsupport 77, 78.

Each of the second active joints 108 comprises a carrier 116 pivotallycoupled to one of the swivel yokes 110. The carriers 116 have internallythreaded throughbores 117 to receive lead screws 150 of the front twoactuators 21, 22, as described further below. Each of the carriers 116also comprises opposed trunnions 118 that allow the carriers 116 topivot relative to the swivel yokes 110 about pivot axes PA (see FIG. 9 )by being seated in pockets in the swivel yokes 110. In some versions,for each of the second active joints 108, the swivel axis SA intersectsthe pivot axis PA to define a single vertex about which the actuators21, 22 move in two degrees of freedom.

Covers are fastened to the swivel heads 112 and define one of thepockets, while the swivel head 112 defines the other pocket. Duringassembly, the carriers are first positioned with one of the trunnionsplaced in the pocket in the swivel head 112, and the cover is thenfastened over the other trunnion such that the carrier is capturedbetween the cover and the swivel head 112 and is able to pivot relativeto the swivel yoke 110 via the trunnions and pockets. Owing to theconfiguration of the swivel yokes 110 and the associated carriers, i.e.,the carriers ability to swivel about the swivel axes SA and pivot aboutthe pivot axes PA, the second active joints 108 allow two degrees offreedom of movement of the front two actuators 21, 22 relative to thebase 74. Other joint arrangements between the front two actuators 21, 22and the base 74 are also possible.

The active joints also comprise a third active joint 124 coupling therear (third) actuator 23 to the base 74 of the hand-held portion 16. Inthe version shown, the third active joint 124 is supported at the jointsupport 79. The third active joint 124 comprises a pivot housing 126fixed to the joint support 79 of the base 74.

The third active joint 124 comprises a carrier pivotally coupled to thepivot housing 126 via trunnions. Fasteners having pockets attach toeither side of the pivot housing 126 via throughbores to engage thetrunnions. The fasteners are arranged such that the carrier is able topivot via the trunnions being located in the pockets after assembly. Thecarrier has an internally threaded throughbore to receive a lead screw150 of the rear actuator 23, as described further below. Owing to theconfiguration of the pivot housing 126 and associated carrier, i.e., theability of the associated carrier to only pivot about the pivot axis PA(e.g., and not swivel), the third active joint 124 allows only onedegree of freedom of movement of the rear actuator 23 relative to thebase 74. Other joint arrangements between the rear actuator 23 and thebase 74 are also possible.

Each of the actuators 21, 22, 23 comprises a housing. The housingcomprises a canister and a cap threadably connected to the canister. Thepivot yokes 106 that form part of the first active joints 92 are fixedto the housings such that the housings and pivot yokes 106 are able tomove together relative to the tool support 18 via the first activejoints 92. The caps capture annular shoulders of the pivot yokes 106 tosecure the pivot yokes 106 to the canisters.

In some versions, the pivot yokes 106 and canisters comprise one or morealignment features to align each pivot yoke 106 to its respectivecanister in a predefined, relative orientation. Such alignment featuresmay comprise mating portions, keys/keyways, or the like. Duringassembly, the pivot yoke 106 may first be secured to the canister in itspredefined, relative orientation, and the cap may then be threaded ontothe canister (e.g., via mating outer and inner threads) to trap thepivot yoke 106 to the canister at the predefined, relative orientation.This predefined relationship may be helpful in routing or aligning theflex circuits FC, preventing rolling of the pivot yoke 106 relative tothe canister, or for other purposes.

Each of the actuators 21, 22, 23 also comprises a motor disposed in eachhousing. The motor has a casing disposed in the housing and a motorwinding assembly disposed within the casing. The motor winding assemblymay also be aligned in a predefined, relative orientation to thecanister, such as via a set screw or other alignment feature, such asthose described above. Each motor also has a rotor fixed to the leadscrew 150. The lead screw 150 is supported for rotation in the housingby one or more bushings or bearings. The rotor and associated lead screw150 are configured to rotate relative to the housing upon selectiveenergization of the motor. The lead screws 150 have fine pitch and leadangles to prevent backdriving (i.e., they are self-locking). As aresult, a load placed on the tool 20 does not easily back drive themotor. In some examples, the lead screws 150 have an 8-36 class 3 threadthat results in a lead of from 0.02 to 0.03 inches/revolution. Otherthread types or sizes may also be employed.

Each of the actuators 21, 22, 23 may be controlled by a separate motorcontroller. Motor controllers may be wired separately to the actuators21, 22, 23, respectively, to individually direct each actuator 21, 22,23 to a given target position. In some examples, the motor controllersare proportional integral derivative (PID) controllers. In someexamples, the motor controllers may include cascaded control loopsrelating to position, velocity, and torque (current). Additionally, oralternatively, the motor controller may only include of a torque(current) control loop. In another example, the position control loopmay directly feed the torque (current) control loop. Each of thesecontrol stages may be implemented as a PID controller, state spacecontroller, or utilize alternate or additional control techniques (e.g.,velocity feedforward, torque feedforward, etc.). In some cases, thetorque (current) control loop is implemented using field-orientedcontrol and space vector modulation. The stages of the control loopcould be distributed between various components of the system. In someexamples, the position loop and velocity loop are implemented in theinstrument controller and the torque control loop is implementeddirectly in the control boards 31 as part of the control housing 29 onthe instrument 14, mitigating the impact of data communication latencyfrom the instrument 14 through the connection to the console 33, sincethe current control loop does not require any data feedback via theconsole 33. The position control loop and velocity control loop are notas sensitive to the communication latency and can be implemented in theconsole 33. In some examples, the motor controllers can be integratedwith or form part of the instrument controller 28. For ease ofillustration, the motor controllers shall be described herein as beingpart of the instrument controller 28.

A power source provides, for example, 32 VDC power signals to the motorsvia the console 33. The 32 VDC signal is applied to the motors throughthe instrument controller 28. The instrument controller 28 selectivelyprovides the power signal to each motor to selectively activate themotors. This selective activation of the motors is what positions thetool 20. The motors may be any suitable type of motor, includingbrushless DC servomotors, permanent magnet synchronous motors, otherforms of DC motors, or the like. The power source also supplies power tothe instrument controller 28 to energize the components internal to thepinstrument controller 28. In some examples, the actuator motor may be a3-phase, brushless motor. The actuator motor may be a DC motor. Theactuator motor may be a permanent magnet synchronous motor. Each of theactuator motors may be configured with a sinusoidal back-EMF, configuredto achieve limited mechanical cogging, allowing smooth and particularmotion, limiting torque ripple. However, other motor types arecontemplated. It should be appreciated that the power source can provideother types of power signals such as, for example, 12 VDC, 24 VDC, 40VDC, etc. The instrument may use electronic switches, e.g., MOSFETs orGaN FETs to PWM the voltage signals to the 3-phase motor on/off at ahigh frequency, e.g., typically at a rate of at least 16 kHz, up to 256kHz or higher.

In one possible implementation, one or more sensors S (see also FIG. 7 )transmit signals back to the instrument controller 28 so that theinstrument controller 28 can determine a current position or angle ofthe associated actuator 21, 22, 23 (i.e., a measured position). Thelevels of these signals may vary as a function of the rotationalposition of the associated rotor. In one implementation, the sensor(s) Smay resolve the rotational position of the rotor within a given turn ata high resolution. These sensors S may be Hall-effect sensors thatoutput analog or digital signals based on the sensed magnetic fieldsfrom the rotor, or from other magnets placed on the lead screw 150(e.g., the 2-pole magnet A low voltage signal, e.g., 5 VDC, forenergizing the Hall-effect sensors may be supplied from the motorcontroller associated with the motor with which the Hall-effect sensorsare associated. In some examples, two Hall-effect sensors are disposedin the housing and spaced 90 degrees apart from each other around therotor to sense joint position so that the instrument controller 28 isable to determine the position and count incremental turns of therotor). In some versions, the Hall-effect sensors output digital signalsrepresents incremental counts. Various types of motors and sensorarrangements are possible. In some examples, the motors are brushless DCservomotors and two or more internal Hall-effect sensors may be spaced90 degrees, 120 degrees, or any other suitable spacing from each otheraround the rotor. The sensors S may also comprise absolute orincremental encoders, which may be used to detect a rotational positionof the rotor and to count turns of the rotor. Other type of encoders maybe also used as the one or more sensors. The sensors may be placed atany suitable location on the actuator and its surrounding componentssuitable to determine the position of each actuator as it is adjusted,such as on the housing, nut, screw, etc. In yet another configuration,sensorless motor control may be utilized. In such an implementation, theposition of each rotor may be determined by measuring the motor'sback-emf or inductance. One suitable example may be found in U.S. Pat.No. 7,422,582, which is hereby incorporated by reference in itsentirety.

In some examples, the sensors or encoders may measure position feedbackfor joint position control or to determine the position of the toolsupport 18 relative to the hand-held portion 16 when used in conjunctionwith a kinematic model of the instrument 14. In some examples, thesensors or encoders rely on a multi-turn measurement, which accumulatesfrom revolution to the next, used to determine an absolute position ofthe actuator 21, 22, 23 along its axis and is used in conjunction withthe known pitch (i.e. revolutions per inch of the leadscrew).Additionally, or alternatively, the sensors or encoders may be used todetermine the “electrical angle of the rotor” for use in electroniccommutation of the motor. For example, the sensors or encoders may beused to determine a rotor position and apply appropriate energizationsignals to achieve optimal (efficient) torque generation. In thisexample, the sensors or encoders may utilize a single turn or sub-turn(within one electrical revolution) measurement that rolls over eachelectrical revolution. The number of electrical revolutions is equal tothe number of mechanical revolutions divided by the number of magneticpoles of the motor (e.g. number of pole pairs). However, it iscontemplated that a sensor-less method be implemented.

In some examples, output signals from the Hall-effect sensors are sentto the instrument controller 28. The instrument controller 28 monitorsthe received signals for changes in their levels. Based on these signalsthe instrument controller 28 determines joint position. Joint positionmay be considered the degrees of rotation of the rotor from an initialor home position. The rotor can undergo plural 360° rotations. The jointposition can therefore exceed 360°. A scalar value referred to as acount is representative of joint position from the home position. Therotors rotate in both clockwise and counterclockwise directions. Eachtime the signal levels of the plural signals (analog or digital) undergoa defined state change, the instrument controller 28 increments ordecrements the count to indicate a change in joint position. For everycomplete 360° rotation of the rotor, the instrument controller 28increments or decrements the value of the count by a fixed number ofcounts. In some examples, the count is incremented or decrementedbetween 100 and 3,000 per 360-degree revolution of the rotor. In someexamples, there are 1,024 positions (counts) per 360-degree revolutionof the rotor, such as when an incremental encoder is used to monitorjoint position. Internal to the instrument controller 28 is a counterassociated with each actuator 21, 22, 23. The counter stores a valueequal to the cumulative number of counts incremented or decremented. Thecount value can be positive, zero or negative. In some versions, thecount value defines incremental movement of the rotor. Accordingly, therotors of the actuators 21, 22, 23 may first be moved to knownpositions, referred to as their home positions (described furtherbelow), with the count values being used thereafter to define thecurrent positions of the rotors.

As previously described, the carriers have the internally threadedthroughbores to threadably receive the lead screws 150 so that each ofthe lead screws 150 can rotate relative to a corresponding one of thecarriers to adjust the effective length of a corresponding one of theplurality of actuators 21, 22, 23 and thereby vary the counts measuredby the instrument controller 28. Each of the housings and correspondingcarriers are constrained from relative movement in at least one degreeof freedom to allow the lead screws 150 to rotate relative to thecarriers. More specifically, the lead screws 150 are able to rotaterelative to the carriers owing to: the pivot yokes 106 being unable torotate about the associated active axes AA1, AA2, AA3 (i.e., the pivotyokes 106 are limited from such rotational movement by virtue of theconfiguration of the first active joints 92); and the carriers beingunable to rotate about the associated active axes AA1, AA2, AA3 (i.e.,the carriers are limited from such rotational movement by virtue of theconfiguration of the second active joints 108 and the third active joint124).

Stops 152, such as threaded fasteners and shoulders formed on the leadscrews 150, are fixed to the lead screws 150. The stops 152 are sized toabut the carriers 116 at ends of travel of each lead screw 150.

As previously described, the actuators 21, 22, 23 are activelyadjustable in effective length to enable movement of the tool support 18relative to the hand-held portion 16. One example of this effectivelength is labeled “EL” on the third actuator 23. Here, the effectivelength EL is measured from the pivot axis PA to a center of theassociated first active joint 92. As each actuator 21, 22, 23 isadjusted, the effective length EL changes, by varying how far the leadscrew 150 has been threaded into or out of its associated carrier andthereby changing the distance from the center of the associated carrierto the center of the associated first active joint 92. The actuators 21,22, 23 are adjustable between minimum and maximum values of theeffective length EL. The effective length EL of each actuator 21, 22, 23can be represented or measured in any suitable manner to denote thedistance between the tool support 18 and the hand-held portion 16 alongthe active axes AA1, AA2, AA3 that changes to cause various movements ofthe tool support 18 relative to the hand-held portion 16.

The constraint assembly 24 works in concert with the actuators 21, 22,23 to constrain the movement provided by the actuators 21, 22, 23. Theactuators 21, 22, 23 provide movement in three degrees of freedom, whilethe constraint assembly 24 constrains movement in three degrees offreedom. In the version shown, the constraint assembly 24 comprises thepassive linkage 26, as well as a passive linkage joint 156 that couplesthe passive linkage 26 to the tool support 18.

In one version, as shown in FIG. 9 , the passive linkage joint 156comprises a passive linkage U-joint. The U-joint comprises a first pivotpin 158 and a joint block 160. The first pivot pin 158 pivotallyconnects the joint block 160 to a passive linkage mount 162 of the toolsupport body 80 via a throughbore 164 in the joint block 160. A setscrew 166 may secure the first pivot pin 158 to the passive linkagemount 162. The U-joint also comprises a second pivot pin 170. The jointblock 160 has a crossbore 168 to receive the second pivot pin 170. Thesecond pivot pin 170 pivotally connects a passive linkage pivot yoke 172of the passive linkage 26 to the joint block 160. The second pivot pin170 has a throughbore 171 to receive the first pivot pin 158, such thatthe first pivot pin 158, the joint block 160, and the second pivot pin170 form a cross of the U-joint. The first pivot pin 158 and the secondpivot pin 170 define pivot axes PA that intersect. As a result, thepassive linkage 26 is able to move in two degrees of freedom relative tothe tool support body 80. Other types of passive linkage joints are alsocontemplated, such as a passive linkage spherical joint comprising aball with slot that receives a pin.

The passive linkage 26 comprises a shaft 174 fixed to the passivelinkage pivot yoke 172. The passive linkage 26 also comprises the sleeve76 of the base 74, which is configured to receive the shaft 174 along aconstraint axis CA. The passive linkage 26 is configured to allow theshaft 174 to slide axially along the constraint axis CA relative to thesleeve 76 and to constrain movement of the shaft 174 radially relativeto the constraint axis CA during actuation of one or more of theactuators 21, 22, 23.

The passive linkage 26 further comprises a key to constrain rotation ofthe shaft 174 relative to the sleeve 76 about the constraint axis CA.The key fits in an opposing keyway in the shaft 174 and sleeve 76 torotationally lock the shaft 174 to the sleeve 76. Other arrangements forpreventing relative rotation of the shaft 174 and sleeve 76 are alsocontemplated, such as an integral key/slot arrangement, or the like. Thepassive linkage 26 operatively interconnects the tool support 18 and thehand-held portion 16 independently of the actuators 21, 22, 23. Thepassive linkage is passively adjustable in effective length EL along theconstraint axis CA during actuation of one or more of the actuators 21,22, 23. The sleeve 76, shaft 174, and key 176 represent one combinationof links for the passive linkage 26. Other sizes, shapes, and numbers oflinks, connected in any suitable manner, may be employed for the passivelinkage 26.

In the version shown, the passive linkage joint 156 is able to pivotabout two pivot axes PA relative to the tool support 18. Otherconfigurations are possible.

Also, in the version shown, the first active joints 92 and the passivelinkage joint 156 define pivot axes PA disposed on a common plane.Non-parallel pivot axes PA, parallel pivot axes PA disposed on differentplanes, combinations thereof, or other configurations, are alsocontemplated.

In some versions, the head 84 of the tool support 18 is arranged so thatthe tool 20 is located on a blade plane BP (e.g., blade plane) parallelto the common plane when the tool 20 is coupled to the tool support 18.In some examples, the blade plane BP is spaced from the common plane CPby 2.0 inches or less, 1.0 inches or less, 0.8 inches or less, or 0.5inches or less.

In the version shown, the actuators 21, 22, 23 are arranged such thatthe active axes AA1, AA2, AA3 are in a canted configuration relative tothe constraint axis CA in all positions of the actuators 21, 22, 23,including when in their home positions. Canting the axes AA1, AA2, AA3generally tapers the actuator arrangement in a manner that allows for aslimmer and more compact base 74 and associated grip 72. Otherconfigurations are contemplated, including those in which the activeaxes AA1, AA2, AA3 are not in the canted configuration relative to theconstraint axis CA. Such configurations may include those in which theactuator axes AA1, AA2, AA3 are parallel to each other in their homepositions.

Further configurations of the actuators, active joints, and constraintassembly are possible. It is contemplated that the control techniquesdescribed may be applied to other mechanical configurations notmentioned, in particular those for controlling a tool or saw bladerelative to a hand-held portion in one or more degrees of freedom. Insome versions, the constraint assembly may be absent and the toolsupport 18 of the instrument 14 may be able to move in additionaldegrees of freedom relative to the hand-held portion 16. For example,the instrument may include linear actuators, rotary actuators, orcombinations thereof. The instrument may include 2, 3, 4, 5, 6 or moredifferent actuators arranged parallel or in series.

Virtual Boundaries

The software employed by the control system 60 to control operation ofthe instrument 14 includes a boundary generator 182 (see FIG. 7 ). Theboundary generator 182 may be implemented on the instrument controller28, the navigation controller 36, or on other components, such as on aseparate controller. The boundary generator 182 may also be part of aseparate system that operates remotely from the instrument 14. Referringto FIG. 7 the boundary generator 182 is a software program or modulethat generates one or more virtual boundaries 184 for constrainingmovement or operation of the instrument 14. In some examples, theboundary generator 182 provides virtual boundaries 184 that define avirtual cutting guide (e.g., a virtual saw cutting guide). Virtualboundaries 184 may also be provided to delineate various control regionsas described below. The virtual boundaries 184 may be one-dimensional(1D), two-dimensional (2D), three-dimensional (3D), and may comprise apoint, line, axis, trajectory, plane (an infinite plane or plane segmentbounded by the anatomy or other boundary), volume or other shapes,including complex geometric shapes. The virtual boundaries 184 may berepresented by pixels, point clouds, voxels, triangulated meshes, other2D or 3D models, combinations thereof, and the like. U.S. PatentPublication No. 2018/0333207 and U.S. Pat. No. 8,898,043 areincorporated by reference, and any of their features may be used tofacilitate planning or execution of the surgical procedure.

The virtual boundaries 184 may be used in various ways. For example, thecontrol system 60 may: control certain movements of the tool 20 to stayinside the boundary; control certain movements of the tool 20 to stayoutside the boundary; control certain movements of the tool 20 to stayon the boundary (e.g., stay on a point, trajectory, or plane); controlcertain movements of the tool 20 to approach the boundary (attractiveboundary) or to be repelled from the boundary (repulsive boundary); orcontrol certain functions of the instrument 14 based on a relationshipof the instrument 14 to the boundary (e.g., spatial, velocity, etc.).Other uses of the virtual boundaries 184 are also contemplated.

In some examples, one of the virtual boundaries 184 is a desired cuttingplane, as shown in FIG. 2 . The control system 60 will ultimatelyfunction to keep the tool 20 on the desired cutting plane in someversions. The virtual boundary 184 that controls positioning of the tool20 may also be a volumetric boundary, such as one having a thicknessslightly larger than a blade thickness to constrain a saw blade to staywithin the boundary and on a desired cutting plane, as shown in FIG. 2 .Therefore, the desired cutting plane can be defined by a virtual planarboundary, a virtual volumetric boundary, or other forms of virtualboundary. Virtual boundaries 184 may also be referred to as virtualobjects. The virtual boundaries 184 may be defined with respect to ananatomical model AM, such as a 3D bone model (see FIG. 2 , whichillustrates the anatomical model AM being virtually overlaid on theactual femur F due to their registration). In other words, the points,lines, axes, trajectories, planes, volumes, and the like, that areassociated with the virtual boundaries 184 may be defined in acoordinate system that is fixed relative to a coordinate system of theanatomical model AM such that tracking of the anatomical model AM (e.g.,via tracking the associated anatomy to which it is registered) alsoenables tracking of the virtual boundary 184.

The anatomical model AM is registered to the first patient tracker 54such that the virtual boundaries 184 become associated with theanatomical model AM and associated coordinate system. The virtualboundaries 184 may be implant-specific, e.g., defined based on a size,shape, volume, etc. of an implant or patient-specific, e.g., definedbased on the patient's anatomy. The virtual boundaries 184 may beboundaries that are created pre-operatively, intra-operatively, orcombinations thereof. In other words, the virtual boundaries 184 may bedefined before the surgical procedure begins, during the surgicalprocedure (including during tissue removal), or combinations thereof.The virtual boundaries 184 may be provided in numerous ways, such as bythe control system 60 creating them, receiving them from other sourcesorsystems, or the like. The virtual boundaries 184 may be stored inmemory for retrieval or updating.

In some cases, such as when preparing the femur F for receiving thetotal knee implant IM (see FIG. 1 ), the virtual boundaries 184 comprisemultiple planar boundaries that can be used to delineate multiplecutting planes (e.g., five cutting planes) for the total knee implantIM, and are associated with a 3D model of the distal end of the femur F.These multiple virtual boundaries 184 can be activated, one at a time,by the control system 60 to constrain cutting to one plane at a time.

The instrument controller 28 or the navigation controller 36 track thestate of the tool 20 relative to the virtual boundaries 184. In oneexample, the state of the TCP coordinate system (e.g., pose of the sawblade) is measured relative to the virtual boundaries 184 for purposesof determining target positions for the actuators 21, 22, 23 so that thetool 20 remains in a desired state. In some cases, the control system 60controls the instrument 14 in a manner that emulates the way a physicalhandpiece would respond in the presence of physical boundaries.

Referring back to FIG. 7 , two additional software programs or modulesrun on the instrument controller 28 or the navigation controller 36. Onesoftware module performs behavior control 186. Behavior control 186 isthe process of computing data that indicates the next commanded positionor orientation (e.g., desired pose) for the tool 20. In some cases, onlythe desired position of the TCP is output from the behavior control 186,while in some cases, the commanded pose of the tool 20 is output. Outputfrom the boundary generator 182 (e.g., a current position or orientationof the virtual boundaries 184 in one or more of the coordinate systems)may feed as inputs into the behavior control 186 to determine the nextcommanded position of the actuators 21, 22, 23 or orientation for thetool 20. The behavior control 186 may process this input, along with oneor more other inputs described further below, to determine the commandedpose.

The instrument controller 28 may control the one or more actuators 21,22, 23 by sending command signals to each actuator 21, 22, 23 to adjustthe tool 20 towards a desired pose. The instrument controller 28 mayknow the entire length that an actuator 21, 22, 23 may adjust the toolsupport 18 relative to the hand-held portion 16. In some examples, theinstrument controller 28 knows the entire length which an actuator 21,22, 23 is capable of adjusting and may send command signals to theactuators 21, 22, 23 to move a measured distance from position toposition. A measured position may be a known position, or a distancebetween the present location of an actuator 21, 22, 23 and the actuatorlimits. Each position that the actuator 21, 22, 23 moves to may be ameasured distance from a positive limit and a negative limit of actuatortravel (i.e. a position between two ends of a lead screw). Theinstrument controller 28 may command the actuators 21, 22, 23 to andfrom measured positions as described below.

The instrument controller 28 may send command signals to each actuator21, 22, 23 to move the actuators 21, 22, 23 from a first position to acommanded position which will place the tool 20 into a desired pose. Insome examples, the commanded position may be determined by theinstrument controller 28 in conjunction with the navigation system 32 todetermine the location of the tool 20 and tool support 18 relative tothe hand-held portion 16, patient trackers PT, 54, 56, a virtual object,such as desired cut plane or a combination thereof and send a signal tothe actuators 21, 22, 23 to adjust a certain distance or commandedposition in order to place the tool 20 into the desired pose. Theinstrument controller may command the actuator 21, 22, 23 to a positionin order to reach the desired adjustment of the tool 20. The instrumentcontroller 28 may control the actuators 21, 22, 23 to linearly move acalculated distance to adjust the tool 20 towards a desired pose. Inother examples, such as when absolute encoders are used, the instrumentcontroller may send signals to the actuators 21, 22, 23 to place eachactuator 21, 22, 23 into a commanded position based on the knownlocation of the tool support 18 relative to the hand-held portiondetermined by the absolute encoder.

The instrument controller 28 may know the entire length that an actuator21, 22, 23 may adjust the tool support 18 relative to the hand-heldportion 16. In some examples, the instrument controller 28 knows theentire length which an actuator 21, 22, 23 is capable of adjusting andmay send command signals to the actuators 21, 22, 23 to move a measureddistance from position to position (e.g., by commanding a desired amountof linear travel via commanded rotation). A measured position may be aknown position, or a distance between the present location of anactuator 21, 22, 23 and the actuator limits. Each position that theactuator 21, 22, 23 moves to may be a measured distance from a positivelimit and a negative limit of actuator travel (i.e., a position betweentwo ends of a lead screw). The instrument controller 28 may command theactuators 21, 22, 23 to and from positions as described below. Theinstrument controller may command the actuator 21, 22, 23 to a positionin order to reach the desired adjustment of the tool 20. The instrumentcontroller 28 may control the actuators 21, 22, 23 to linearly move acalculated distance to adjust the tool 20 towards a desired pose. Inother examples, such as when absolute encoders are used, the instrumentcontroller may send signals to the actuators 21, 22, 23 to place eachactuator 21, 22, 23 into a commanded position based on the knownlocation of the actuator 21, 22, 23 between the respective actuatortravel limits determined by the absolute encoder. Alternately, in oneexample, an incremental encoder may be used in conjunction with a homingprocedure performed during system setup as described in U.S. PatentPublication No. 2017/0156799, which is hereby incorporated by reference.A homing procedure may be used, placing the actuators 21, 22, 23 and thejoints at their centered position, and subsequently determines theabsolute offsets of the incremental encoders. By determining the offsetsof the incremental encoders, the incremental encoders may perform asabsolute encoders going forward.

In some examples, when a homing position is used, the homing processestablishes the initial rotor positions (zero position) of the actuators21, 22, 23. The home position is effectively a position of the rotor 148that provides the greatest possible travel in each direction along theactive axis AA1, AA2, AA3. In some examples, the home position isgenerally located such that a home point HP of the lead screw 150,centrally disposed halfway between the stops 152, is centrally disposedin the associated carrier 116. Even when the homing procedure is notused, such as with absolute encoders, setting the actuators 21, 22, 23to the home point HP prior to or after executing other modes (such asapproach mode, described further below) may be included. The instrumentcontroller 28 may be configured to control the actuators 21, 22, 23 totheir home positions between minimum and maximum values of the effectivelengths EL of the actuators 21, 22, 23.

When in the home position, the amount of adjustability of the actuators21, 22, 23 is maximized to keep the tool 20 at a desired pose. Variouslevels of adjustment are possible depending on the particular geometryand configuration of the instrument 14. In some examples, when all theactuators 21, 22, 23 are in their home positions, the tool 20 may beadjusted in pitch orientation about +/−18° relative to the homeposition, assuming zero changes in the roll orientation and no z-axistranslation. In some examples, when all the actuators 21, 22, 23 are intheir home positions, the tool 20 may be adjusted in roll orientationabout +/−33° relative to the home position, assuming zero changes in thepitch orientation and no z-axis translation. In some examples, when allthe actuators 21, 22, 23 are in their home positions, the tool 20 may beadjusted in z-axis translation about +/−0.37 inches relative to the homeposition, assuming zero changes in the pitch orientation and rollorientation. The tool 20, of course, may be adjusted in pitch, roll, andz-axis translation simultaneously, sequentially, or combinations thereofduring operation. In certain instances, the home position also refer tothe tool support being in the home position. When the tool support is inthe home position, each of the actuators in the actuator assembly arealso in their home position—the adjustability of each of the actuatorsbeing maximized to provide for the greatest movement in all degrees offreedom.

In some examples, when one or more of the actuators 21, 22, 23 havereached their mechanical or software-imposed limit, the instrumentcontroller 28 may require the hand-held portion 16 to be adjusted inorder to bring the tool 20 back into a range where the actuators arecapable of adjusting the tool 20 towards the desired pose. In such acase, a simulated commanded position may be used to indicate to a userhow to move the hand-held portion 16 in order to bring the tool 20 andactuators 21, 22, 23 back into alignment with the desired pose. Asimulated commanded position may be a position determined by theinstrument controller 28 in conjunction with navigation data from thenavigation system 32 in which the hand-held portion 16 must be moved toadjust the tool 20 towards a desired pose without adjusting theactuators 21, 22, 23. The simulated commanded position works with theone or more displays 38 to signal to a user that the hand-held portion16 needs to be moved in particular way to place the tool 20 at thedesired pose. The visual indicators described herein may be used tosignal to a user to move the hand-held portion 16 in the same fashion asif the actuators 21, 22, 23 were adjusting the tool 20, but relies onthe user to correct the pose of the tool 20 by manipulating thehand-held portion 16 while the actuators remain in position.

The second software module performs motion control 188. One aspect ofmotion control 188 is the control of the instrument 14. The motioncontrol 188 receives data defining the next commanded pose from thebehavior control 186. Based on these data, the motion control 188determines the next rotor position of the rotors 148 of each actuator21, 22, 23 (e.g., via inverse kinematics) so that the instrument 14 isable to position the tool 20 as commanded by the behavior controller186, e.g., at the commanded pose. In other words, the motion control 188processes the commanded pose, which may be defined in Cartesian space,into actuator positions (such as rotor positions) of the instrument 14,so that the instrument controller 28 can command the motors 142accordingly, to move the actuators 21, 22, 23 of the instrument 14 tocommanded positions, such as commanded rotor positions corresponding tothe commanded pose of the tool 20. In one version, the motion control188 regulates the rotor position of each motor 142 and continuallyadjusts the torque that each motor 142 outputs to, as closely aspossible, ensure that the motor 142 drives the associated actuator 21,22, 23 to the commanded rotor position. This generated commanded pose,which is defined in Cartesian space, may also be used to control thevisual indicators as described below.

In some versions, the instrument controller 28, for each actuator 21,22, 23, determines the difference between a measured position and acommanded position of the rotor 148. The instrument controller 28outputs a target current (proportional to a torque of the rotor),changing the voltage to adjust the current at the actuator from aninitial current to the target current. The target current effectuates amovement of the actuators 21, 22, 23, moving the tool 20 from themeasured pose to the commanded pose. This may occur after the commandedpose is converted to joint positions. In one example, the measuredposition of each rotor 148 may be derived from the sensor S describedabove, such as an encoder.

The boundary generator 182, behavior control 186, and motion control 188may be sub-sets of a software program. Alternatively, each may besoftware programs that operate separately or independently in anycombination thereof. The term “software program” is used herein todescribe the computer-executable instructions that are configured tocarry out the various capabilities of the technical solutions described.For simplicity, the term “software program” is intended to encompass, atleast, any one or more of the boundary generator 182, behavior control186, or motion control 188. The software program can be implemented onthe instrument controller 28, navigation controller 36, or anycombination thereof, or may be implemented in any suitable manner by thecontrol system 60.

A clinical application 190 may be provided to handle user interaction.The clinical application 190 handles many aspects of user interactionand coordinates the surgical workflow, including pre-operative planning,implant placement, registration, bone preparation visualization, andpost-operative evaluation of implant fit, etc. The clinical application190 is configured to output to the displays 38. The clinical application190 may run on its own separate processor or may run alongside theinstrument controller 28 or the navigation controller 36. In oneexample, the clinical application 190 interfaces with the boundarygenerator 182 after implant placement is set by the user, and then sendsthe virtual boundaries 184 returned by the boundary generator 182 to theinstrument controller 28 for execution.

An initial location of the base coordinate system BCS can be determinedbased on a known geometric relationship between the tool supportcoordinate system TCS and the base coordinate system BCS when theactuators 21, 22, 23 are in their home positions or other predeterminedposition. This relationship changes when the actuators 21, 22, 23 areadjusted and the associated changes can be determined based on thekinematics of the robotic system 10 (e.g., which establishes a dynamictransformation between these coordinate systems). Alternatively, oradditionally, another tracker could be attached and fixed with respectto the base coordinate system BCS to directly track a pose of the basecoordinate system BCS relative to the tool support coordinate systemTCS. Thus, the robotic system 10 knows the position of the tool 20, suchas in the home position and its relation to the pose of the hand-heldportion 16. Accordingly, when the tool 20 is moved by the user and itspose is tracked using the tool tracker 52, the robotic system 10 alsotracks the pose of the hand-held portion 16 and its base coordinatesystem BCS. In some examples, as a result of prior calibrationprocesses, the position of the tool 20 relative to the tool support 18is assumed to be known.

In some versions, the home position is determined by first determining apose of the hand-held portion 16 (e.g., of the base coordinate systemBCS) relative to the tool support 18 (e.g., relative to the tool supportcoordinate system TCS) in a common coordinate system by employing aseparate tracker fixed to the hand-held portion 16. This spatialrelationship between the hand-held portion 16 and the tool support 18could also be determined by registration using the pointer 57 and knowncalibration divots on the hand-held portion 16, or via other navigationmethods. The current rotor position of each of the actuators 21, 22, 23can then be derived from this spatial relationship based on thekinematics of the instrument 14. Knowing the current rotor positions andmeasuring changes from the current rotor positions using the encoders(and corresponding encoder signals), the instrument controller 28 canthereafter operate each of the actuators 21, 22, 23 until they reachtheir home positions. The home positions can be stored in the memory ofthe instrument controller 28.

In essence, the instrument controller 28 uses tracking data obtained bythe navigation system 32 from the tracker 52 coupled to tool support 18and the hand-held portion 16 on the instrument 14 to determine theposition of the actuators 21, 22, 23 so that, thereafter, theincremental encoders can operate as absolute encoders.

Instructional data packets are sent, for example, to the motorcontrollers, such as from the console 33 or another component of theinstrument controller 28. These instructional data packets include thetarget position for the rotors 148 of the motors 142 (or target positionof the actuator). Here, each target position may be a positive ornegative number representative of a targeted cumulative count for theassociated rotor 148. The console 33 or other component of theinstrument controller 28 generates and sends these instructional datapackets to each motor controller at the rate of one packet every 0.05 to4 milliseconds. In some examples, each motor controller receives aninstructional data packet at least once every 0.125 milliseconds.

During use, when the robotic system 10 determines a pose (a currentpose) of the tool 20 with the navigation system 32 by virtue of the tooltracker 52 being located on the tool support 18. The instrumentcontroller 28 may also determine a current position of each of theactuators 21, 22, 23 based on an output encoder signal from the one ormore encoders located on each of the actuators 21, 22, 23. Once thecurrent position of each of the actuators 21, 22, 23 is received, theinstrument controller 28 may calculate a current pose of the hand-heldportion 16 (e.g., a current pose of the base coordinate system BCS withrespect to a desired coordinate system, such as the TCP coordinatesystem using forward kinematics to convert from the actuator positionsto the pose (TCP with respect to BCS)). Once the instrument controller28 has the current relative poses of the tool support 18 and thehand-held portion 16 in the desired coordinate system, the instrumentcontroller 28 may then determine a commanded pose of the tool 20 basedon the current pose of the tool 20 as determined by the navigationsystem 32, the current pose of the hand-held portion 16 calculated bythe current position of each of the actuators 21, 22, 23, and based on aposition or orientation of a planned virtual object, subject as adesired cutting plane. The instrument computes a pose (a commanded pose)of TCP with respect to BCS that results in the TCP being on the desiredplane or aligned with the planned virtual object. The instrumentcontroller 28 may send command instructions to the actuators 21, 22, 23to move to a commanded position, thereby changing the pose of the toolsupport 18 and tool 20. In one example, the commanded pose of the tool20 is further based on a target cut plane so the instrument controller28 calculates the current pose of the tool support 18 and the currentpositions of the actuators 21, 22, 23 in order to determine the currentpose of the hand-held portion 16. Once the current pose of the toolsupport 18, current positions of the actuators 21, 22, 23, and thecurrent pose of the hand-held portion 16 are known, the instrumentcontroller 28 can send command signals to the actuators 21, 22, 23 toadjust the tool support 18 and tool 20 based on the desired plane. Thecontroller computes the commanded pose assuming that, momentarily(during a single iteration) the pose of the hand-held portion (BCS) isstationary relative to patient anatomy. By updating the correspondingposes each time, the actual movement of BCS is adjusted for.

Turning to FIG. 10 , the exemplary control is described with respect tothe various transforms. The TCP is determined by tracking the tool 20with the tool tracker 52 in C (C-TT) and determining a transform betweentool tracker 52 and the TCP of the tool 20 (TT-TCP), such as the saw,using registration data. Similarly, the patient is tracked using thepatient tracker PT (shown as 54) in the C(LCLZ-PT). A transform (PT-TP)is determined between the patient tracker PT and each planned virtualobject (TP) using registration data and planning information. Asdescribed above, a transform between BCS and TCP (BCS-TCP) is computedbased on the current positions of each actuator (described above). Thetransform between BCS and TCP is utilized to relate the variouscoordinate systems back to the hand-held portion 16, since the commandedpose may be determined relative to the BCS. Conceptually, the commandedpose, is an update to the BCS to TCP transform which results in the TCPbeing aligned with the planned virtual object (the target plane TP),which may include one or more virtual boundaries 184, in this example.

It should be appreciated that the phrase ‘TCP’ of the instrument” hasbeen used interchangeably with the phrase ‘position of the saw blade’.Thus, in any instance where the TCP of the instrument/tool is used, itmay be substituted with the position of the saw blade and vice-versa. Ofcourse, it is also contemplated that the position of the ‘saw blade’ mayalternatively be a position of a tool of any suitable configuration,such as a drill, bur, guide tube, pin, and the like.

Throughout this description, unless otherwise noted, any instance ofpose may be a commanded pose, a current pose, a past pose, or a pastcommanded pose. While each of these poses may be different from oneanother, due to the frequency of control, the difference in position ororientation between these poses may be minimal in each controliteration.

It should be understood that the combination of position and orientationof an object is referred to as the pose of the object. Throughout thisdisclosure, it is contemplated that the term pose may be replaced byposition or orientation and vice-versa to achieve suitable alternativesof the concepts described herein. In other words, any use of the termpose can be replaced with position and any use of the term position maybe replaced with pose.

Operation

During operation, the robotic system 10 is initially powered up and thesoftware application for operating the system is started. The trackers52, 54, 56, PT are initialized and the trackers 52, 54, 56 are placed onthe instrument 14 and on the target anatomy (e.g., femur F and tibia T).With the patient trackers 54, 56 mounted to the anatomy, the anatomy orassociated images/models are registered to the patient trackers 54, 56using known registration techniques. This may require the user to touchcertain surfaces or landmarks on the anatomy with the pointer 57. Forexample, this may require the user to touch several points on thesurface of the anatomy while pressing a select button on the pointer 57or pressing a foot switch of the navigation system 32. This “paints” thepoints on the surface in the navigation system 32 for matching with thepre-operative or intra-operative image/model of the anatomy. Thepre-operative image or the intra-operative image/model of the anatomy isloaded in the navigation system 32. The tracked portion of the anatomyis registered to the pre-operative or intra-operative image/model. Byextension, this allows the robotic system 10 to, as the anatomy moves,present a graphical representation of the actual position andorientation of the anatomy on the displays 38.

In a calibration procedure, the orientation and location of the tooltracker 52 is calibrated relative to the tool support 18 by reference tothe fixed and known locations of the calibration divots CD or otherreference points. In some examples, one or more tool trackers 52 may belocated on the tool support 18, the hand-held portion 16, or both sothat the position of the tool support 18 or the hand-held portion 16 aretracked by the navigation system 32. In examples in which the tooltracker 52 is integrated into the instrument 14, then such calibrationwould be unnecessary since the relative location of the tool tracker 52to the tool support 18 is known.

The virtual objects (e.g., virtual boundaries 184) being used to controloperation of the instrument 14 are also defined. Software running oninstrument controller 28 (e.g., the boundary generator 182) generates aninitial definition of the virtual objects. The user may have the abilityand option to adjust the placement of the virtual objects as may benecessary.

In one exemplary configuration, the control system 60 defines variousregions at predefined distances or positions from the target site oranatomy. Each of these regions may be defined in the coordinate systemassociated with the anatomy or virtual boundaries 184. In some cases,these regions are defined as spheres or other geometric primitives aboutthe target site or the anatomy. In other examples, the regions (andothers described below) may be defined with respect to the instrument14, tool support 18, the hand-held portion 16, the tool 20, the target,or a combination thereof. The control system 60 may control theinstrument 14 when the regions defined by the hand-held portion 16, thetool support 18, the tool 20, the target, or a combination thereofapproach a specific virtual boundary.

In particular, the instrument controller 28 generates a set of targetrotor positions to which the rotors 148 integral to the motors 142 mustrotate to maintain the tool 20 at the desired pose. In other words, ifthe user moves the hand-held portion 16 in a manner that causes the tool20 to move away from its desired pose, this is detected by thenavigation system 32. In response to this movement, the instrumentcontroller 28 determines, based on data from the navigation system 32,how far the tool 20 has moved away from the desired pose and compensatesfor such movement by driving the actuators 21, 22, 23 as needed to bringthe tool 20 back to the desired pose. It should be appreciated that suchdeviations from the desired pose will usually be small, as theinstrument controller 28 will be operating at a high frequency (e.g.,frame rate) to continuously account for such deviations in substantiallyreal-time.

The target rotor positions are determined based on the relationshipsbetween actuation of the actuators 21, 22, 23 and resulting movement(e.g., kinematics). For example, if the desired pose requires z-axistranslation relative to the hand-held portion 16, there is a first orderrelationship between the extent to which the tool 20 will move in thez-axis and the amount of rotation of each rotor 148 (e.g., how manycounts are associated with such z-axis movement). There are alsorelationships between the extent to which the tool 20 will change itspitch orientation in response to actuation of the third actuator 23alone, or in combination with one or both of the first and secondactuators 21, 22. Lastly, there are relationships between the extent towhich the tool 20 will change its roll orientation in response toactuation of one or both of the first and second actuators 21, 22, withor without actuation of the third actuator 23. Based on theserelationships, the instrument controller 28 determines the target rotorposition for each rotor 148 that is required to maintain the desiredpose of the tool 20. The instrument controller 28 operates the motors142 based on these target rotor positions. For example, the console 33may transmit packets to the motor controllers containing these targetrotor positions, and each motor controller may apply appropriateenergization signals to the associated motor 142. These energizationsignals cause the rotation of the rotor 148 that results in therepositioning of the lead screw 150 that displaces the tool support18/tool 20 as needed to maintain the tool 20 in the desired pose.

As described previously, the actuators 21, 22, 23 are held at the homeposition or other predetermined position as the user arranges thehand-held portion 16 toward the desired plane. By keeping the actuators21, 22, 23 at their home position or other predetermined position, auser may find it easier to adjust and line up the tool 20 with thedesired plane and instrument pose relative to the target. However, whenthe tool is at the desired pose, the visual indicator is intended toguide the user as to how to move the hand-held portion 16 to provide theinstrument 14 with sufficient adjustability by keeping the actuators 21,22, 23 near their home positions or other predetermined position. Forexample, the user may need to move the hand-held portion 16 upwardly inthe z-axis direction to move all the actuators 21, 22, 23 closer totheir home positions, while keeping the tool 20 at the desired pose. Inother words, the actuators 21, 22, 23 may be nearly fully extended. Toaccomplish this, the directional indication from the visual indicator isupward. In this case, the visual indicator is actually guiding the userto move the hand-held portion 16 upward so that the actuators 21, 22, 23operate toward their home positions to maximize adjustability of theactuators 21, 22, 23. As the user moves the hand-held portion 16 upward,the actuators 21, 22, 23 continue to operate to keep the tool 20 at thedesired pose (e.g., on the virtual boundary 184). As a result, theactuators 21, 22, 23 retract, such as retracting toward their homepositions. Ideally, when the user starts cutting bone, a maximum amountof travel is available in either direction for each actuator 21, 22, 23.Otherwise, if one or more of the actuators 21, 22, 23 have nearlyreached their available travel in either direction, then even slightmovements of the hand-held portion 16 may result in the instrumentcontroller 28 being unable to keep the tool 20 at the desired pose, andan inaccurate cut could be made.

Additionally or alternatively, in some versions, the tool 20 may move tothe desired pose and then the user may adjust the hand-held portion 16to a more comfortable position within the threshold value of availabletravel of actuators 21, 22, 23 to perform a cut while the tool 20 ismaintained at its desired position. The user may then select, byactivating an input device, such as a button or a foot switch, orselecting on a touchscreen, to move into a free-hand mode where the poseof the hand-held portion 16 relative to the pose of the tool 20 is heldor frozen in its current spatial relationship. It is contemplated thatthe held pose of the hand-held portion 16 relative to the pose of thetool 20 changes the virtual threshold value of the actuators 21, 22, 23,restraining actuator movement by to maintain the held pose once the userhas selected an operating mode.

Visual Guidance

As shown in FIG. 8 , the robotic system 10 also includes visualindicator 201. Other exemplary visual indicators are shown in FIGS.21-24, 26-42C. The visual indicator may be configured differentlydepending on user preference. In one configuration and with reference toFIG. 8 , the visual indicator may be coupled to the instrument. Moreparticularly, the visual indicator may be coupled to the tool support,the hand-held portion, or a combination thereof. Alternatively, withreference to FIG. 1 , the visual indicator may be positioned separatelyfrom the instrument, such as on the UI. For example, the visualindicator may take the form of a display screen positioned in theoperating room for ease of view by the surgeon. More particularly, thevisual indicator may be in the form of a display screen coupled to anavigation cart. Depending on the location of the visual indicatorrelative to the controller(s) of the system, the visual indicator may becoupled to a transmitter unit. The transmitter unit can include aprocessing portion and a power supply. As should be appreciated, any ofthe above components may be distributed across one or more separatedevices or locations. The transmitter unit may be electrically coupledto the visual indicator, so as to establish a wired or wirelesselectrical connection between the transmitter unit and the displayvisual indicator.

The use of the visual indicator may provide additional robustness indesign by avoiding poses that could lead to interruption of the surgicalprocedure, such as avoiding poses where the limits of the range ofmotion in one or more degrees of freedom have been met. This is due tothe fact that the control system may be configured to determine whetheran override to the drive motor is necessary

As the control system 60 determines the commanded position or commandedjoint angle for each actuator to move the TCP to the target pose, thecontrol system 60 may control activation of the drive motor M based onone or more positions of the plurality of actuators or the tool support.The one or more actuator positions may be based on the commanded jointposition of at least one actuator, a measured position of at least oneactuator, a previous commanded position of at least one actuator, aprevious measured position of at least one actuator, or combinationsthereof. In one example, the drive motor M is controlled based on acommanded position of at least one of the actuators 21, 22, 23. Thecommanded joint position of the at least one actuator 21, 22, 23 iscompared with an actuator motor override limit of the at least oneactuator 21, 22, 23. The motor override limit may be a value, or aseries of values defining the outer bounds of a range. Although thisexample demonstrates monitoring one actuator, the control system maymonitor the commanded position and the actuator motor override limits ofeach actuator 21, 22, 23. The upper limit and the lower of the actuatormotor override limit may be values corresponding to the position of theactuator relative to the operational range of each actuator. The upperlimit may correspond to a maximum allowed traveled in a first direction,and the lower limit may correspond to a maximum allowed travel in asecond, opposite direction before the drive motor parameter will beadjusted. More specifically, the control system 60 controls a motorparameter of the drive motor M at a first value and a second value basedon whether the commanded joint position would keep the actuator positionbetween the upper limit and lower limit of the motor override limits.The control system 60 may control one or more motor parameters of thedrive motor M, the one or more motor parameters may be a speed, atorque, an operation time, a current, or a combination thereof. In oneexample, the motor parameter controlled by the control system 60 is themotor speed, the first value being zero (drive motor M is off) and thesecond value being greater than zero (drive motor M is on). The controlsystem 60 switches the motor parameter between the first and secondvalues based on the commanded position of the actuator 21, 22, 23. Whenthe commanded position of the actuator 21, 22, 23 places the actuatorwithin the upper limit and lower limit of the motor override limits, thecontrol system 60 may command the second value of the drive motorparameter, allowing the drive motor M to be actuated or continue to beenergized. When the commanded actuator position is between the lower andupper motor override limits, a joint velocity command override is notmodified

In some examples, the drive motor override may be implemented as alookup table or function that is evaluated based on the actuatorposition (P) data received. For the example of the joint positionvelocity override, this would allow the speed of the drive motor to getramped down proportionally as the joint position approaches its motoroverride limit. In some examples, there may be no modification when theactuator position is within the lower and upper motor override limits.In other examples, proportional ramp down of drive motor M speed whenone or more of the actuators 21, 22, 23 are at a position between 80%travel to 95% travel range, and may be fully disabled above 95% travel,which may provide a continual and gradual feedback to the user that thetool 20 is approaching the operational limits (the lower and upper motoroverride thresholds). In such an implementation, there may be aplurality of lower motor override thresholds and a plurality of uppermotor override threshold, each threshold corresponding to a motorparameter (such as a motor speed) In some cases, the drive motor M speedmay not be reduced to zero completely, but rather to a fixed lowerspeed, allowing the surgeon to be alerted but allowing a determinationas to whether to proceed at the surgeon's discretion. When the commandedposition of the actuator 21, 22, 23 places the actuator outside of theupper limit and lower limit of the motor override limit, the controlsystem 60 may command the first value of the drive motor parameter,preventing the drive motor M from being actuated or continuing to beenergized. The motor override limits for each actuator may be differentthan the joint thresholds for each actuator described above. Forexample, the motor override limits may define a narrower range than arange defined the joint thresholds, and the range of the motor overridelimits may be wholly within the joint threshold range. By utilizing thevisual indicator, a user can more easily avoid the upper and lowerlimits of the motor override limits attributed to each actuator, andminimize interruptions caused by shutting off of the drive motor.

Different control methodologies may be used to control the plurality ofactuators to place the tool at a desired location, such as target plane,including but not limited to impedance control, admittance control,position control, or a hybrid control using multiple different controlimplementations. While an admittance control implementation is describedin detail, it should be appreciated that other methodologies may beused. In an admittance control mode, the control system accepts forceinput (virtual or measured) and commands position (or motion) output.For example, for admittance control, the system models a force or torqueat a particular location on a virtual mass and acts to modify the poseof the virtual mass to achieve the desired target state of the tool. Inan impedance control mode, the control system accepts position (ormotion) input and commands a force or torque output. For example, theimpedance control system measures, senses, or calculates a position(i.e., position, orientation, velocity, or acceleration) of theinstrument and may apply an appropriate corresponding torque to each ofthe actuators to achieve the desired target state of the tool. Positioncontrol may also be used to control the plurality of actuators towardsimplementing certain behaviors. It should be appreciated that changes toboth the behavior controller and the motion controller would be neededimplement these control schemes.

The control system may be configured to determine a pose of the of thehand-held portion in a known coordinate system. The pose of thehand-held portion may be a commanded pose, a simulated commanded pose, ameasured pose, a previous commanded pose, a previous measured pose, orcombinations thereof. In one particular implementation, the pose of thehand-held portion is a commanded pose, and the commanded pose of thehand-held portion is a relationship between the saw blade and thehand-held portion. Alternatively, the control system may be configuredto determine a pose of the tool support in the known coordinate systemin a similar way. In the examples described below, the commanded pose iscomputed for the hand-held portion relative to the target plane (TP).Additional detail on the transforms that are utilized to compute thecommanded pose is described with reference to FIG. 10 , and in U.S.Provisional Application No. 63/085,651, filed on Sep. 30, 2020, which ishereby incorporated by reference in its entirety. It should beappreciated that the visual indicator may be controlled based on otherposes, including poses computed relative to different components of thesystem.

Based on the computed pose of the hand-held portion relative to thetarget plane, the control system may determine a pitch value, a rollvalue, an elevation value or combinations thereof. In other words, thecontrol system may determine a position or orientation of the hand-heldportion in one or more degrees of freedom, such as the position intranslation (such as z-axis translation, referred to herein aselevation), the orientation in roll, and the orientation in pitch thatconstitute the commanded pose. Additionally or alternatively, dependingon the nature of the actuator assembly, the positions and orientationsof the hand-held portion may be computed in other degrees of freedom,such as yaw, x-axis and y-axis translation. These values may beexpressed in Cartesian space of the hand-held portion. It should beappreciated that description below is an example of where the visualindicator is controlled based on the positions or orientations of thehand-held portion and the range of motion of the hand-held portion.However, it is also contemplated that similar computations could be madewith respect to other portions of the instrument, such as the toolsupport or the tool. For this reason, throughout the disclosure, anyreference to controlling the visual indicator based on a characteristic(such as pose or position or orientation or range of motion) of thehand-held portion can be replaced with controlling the visual indicatorbased on a characteristic of other parts of the instrument, such ascontrolling the visual indicator based on the pose/position/orientationor range of motion of the tool support or the tool. Examples for theseimplementations have been omitted for brevity.

The control system may also be configured to determine or receive atheoretical range of motion of the hand-held portion relative to thetool support. In certain instances, the theoretical range of motion ofthe hand-held portion may be based on the particular pose of thehand-held portion. This is due to the fact that the range of motion inone or more degrees of freedom may vary based on the position ororientation of the hand-held portion in another degree of freedom. Forexample, the range of motion in the roll degree of freedom and the pitchdegree of freedom may vary based on the position of the hand-heldportion in the elevation degree of freedom. In other words, the range ofmotion in roll may be less at a first elevation value than at a secondelevation value. The theoretical range of motion data set may beobtained empirically or mathematically. One such empirical method may beto plot the actual poses of the hand-held portion in a statisticallysignificant number of poses representing a variety of relationshipsbetween the tool support and the hand-held portion. Variouscurve-fitting algorithms and regressions may be used to plot andcalculate the theoretical range of motion based on the empiricallycollected data set. Alternatively, the theoretical range of motion maybe computed mathematically based on the kinematics of the actuatorassembly.

In one example, the control system may compute the range of motion foreach of a plurality of degrees of freedom independently. For example,the control system compute a range of motion in pitch, a range of motionin roll, and a range of motion in elevation. Referring to FIG. 12 , therange of motion of the hand-held portion may be a volume defined byCartesian model 200 in the known coordinate system. The Cartesian model200 represents a three-dimensional workspace of the hand-held portionrelative to the tool support or vice-versa. The Cartesian model iscomputed in the same coordinate system as the pose used to determine thepitch, roll, translation, etc. of the hand-held portion. The Cartesianmodel is 200 used to understand the theoretical range of motion. TheCartesian model is mapped to the Cartesian coordinates that are used toexpress the pose of the tool support in terms of the pitch value, theroll value, or elevation value, i.e., a first degree of freedom, asecond degree of freedom, or a third degree of freedom. The Cartesianmodel 200 is defined by x, y, and z coordinates and hence, can be mappedto roll values, pitch values, and elevation values. As described above,the Cartesian model 200 representing the three-dimensional workspace ofthe tool support may be derived from empirical data While a diamondshape is shown for the Cartesian model 200, it should be understood thatthe Cartesian model can have suitable three dimensional shape, and isnot necessarily symmetrical. Furthermore, it should be understood thatthe Cartesian model may be represented with a plurality of intersectinglines, the equations for each of those intersecting lines can becalculated based on various regressions from the empirical data or basedon the kinematics of the actuator assembly.

The shapes of the predetermined Cartesian model may be implemented as avolume, such as an octahedron, an asymmetrical octahedron, a sphere, acuboid, a cylinder, etc. Particularly, in some examples, the Cartesianmodel when defined as a volume, may be asymmetrical in shape, such asasymmetrical about a plane position between the tool support 18 and thehand-held portion 16 when each of the actuators are in the homeposition, with the Cartesian volume being greater above the plane thanbelow the plane. In this example, the volume may be defined by aplurality of Cartesian points. This volume may be less than thedexterous workspace (less than all reachable configurations).Alternatively, the predetermined Cartesian model may be defined in eachdegree of freedom separately. For example, the Cartesian model may bedefined with a plurality of Cartesian points. The predeterminedCartesian space may also be defined by one or more orientations, basedon any one, two or three of the axes along which or about which the sawblade can be displaced (x, y, and z).

In essence, the relationship between the Cartesian model 200 used toexpress the pose of the hand-held portion and the Cartesian coordinatesystem used to understand the theoretical range of motion is known. Tosimplify the calculation it will be assumed that the origins of the twoCartesian coordinate systems are aligned with one another or knownrelative to one another, and may be referred to interchangeablythroughout this disclosure. Because the range of motion of certaindegrees of freedom may not be critical depending on the actuatorconfiguration, the position or orientation in every degree of freedomneed not be compared to the theoretical range of motion.

The Cartesian model 200 may be understood to include a plurality oftwo-dimensional slices, each slice representing the range of motion intwo degrees of freedom based on a position or orientation in a thirddegree of freedom. In FIG. 12 , each two-dimensional slice (202′, 202″)represents a range of motion in the pitch degree of freedom and the rolldegree of freedom at a particular elevation value. With reference toFIG. 12 , is readily apparent that the lower elevation slice correspondsto additional range of motion in pitch and roll than the upper elevationslice. As described above with respect to the Cartesian model as awhole, each two-dimensional slice may be represented by a plurality oflines, such as four lines. Each line having an equation defined. Thearea enclosed by the intersections of those lines can be understood asthe two-dimensional slice region.

Referring now to FIGS. 13-20 , with respect to the theoretical range ofmotion of the hand-held portion, the plurality of two-dimensional slices202′″-202″ ″ can be understood as a plurality of two-dimensionalregions, with each region defining its own origin at the particularelevation. Thus, each of the two-dimensional slices can be understood ina polar coordinate system. The outer bounds of the two-dimensionalregions corresponding to pitch and roll values (x1, y1; x2, y2; x*, y* .. . ) at the outermost limits of the range of motion of the hand-heldportion at that particular elevation. The number of two-dimensionalslices is not particularly limited (only two are shown in FIG. 12 ), andmay be plotted at a discrete elevation interval, such as 0.1 mm In otherwords, a two-dimensional region may be computed from the minimum to themaximum possible elevation value, at intervals of 0.1 mm, for the entireCartesian model. Of course, any suitable interval may be used. Thecontrol system may select the two-dimensional region that most closelycorresponds to the elevation value of that commanded pose.

Generally speaking, the control system is configured to control thevisual indicator based on the actual position or orientation of thehand-held portion in one or more degrees of freedom and the range ofmotion in one or degrees of freedom. This may include controlling thevisual indicator based on a position or orientation of the hand-heldportion and the range of motion in a first degree of freedom, based on aposition or orientation of the hand-held portion and the range of motionin a second degree of freedom, and based on a position or orientation ofthe hand-held portion and the range of motion in a third degree offreedom. As mentioned, the visual indicator could also be controlledbased on the positions and orientations in other degrees of freedom.

Furthermore, it should be understood that the control system may beconfigured determine a first pose of the hand-held portion and a firstrange of motion based on the first pose and determine a second pose ofthe hand-held portion, and determine a second range of motion based onthe second pose. It should be understood that the first range of motionand the second range of motion are different and that the first andsecond poses are different from one another, i.e., represent the posesof the hand-held portion at two different instances of time. Because therange of motion in one or more degrees of freedom may be dependent onthe position or orientation of the hand-held portion in another degreeof freedom, the range of motion may be different in the first range ofmotion and the second range of motion. The control system may determinethe position or orientation of the hand-held portion based on the firstpose in the first degree of freedom and control the visual indicatorbased on the first position or orientation and the first range ofmotion; and determine a second position or orientation of the hand-heldportion based on the second pose in the first degree of freedom andcontrol the visual indicator based on the second position or orientationand the second range of motion. For example, the control system maydetermine an orientation of the hand-held portion in roll and a range ofmotion of the orientation of the hand-held portion in roll at a firsttime, and determine an orientation of the hand-held portion in roll anda range of motion of the hand-held portion in roll at a second time,with the roll different between the first time and the second time andthe range of motion in roll also differing between the first time andthe second time, and controlling the visual indicator accordingly. Whilethis example is provided for roll, it should be understood that the samecomputation could be performed in pitch, translation (such aselevation), or other degrees of freedom. This provides for the visualindicator to convey a precise indication of the range of motion of thehand-held surgical instrument at all times, which can lead to betterutilization of the instrument, and less interruption of the surgicalprocedure because the user has moved the instrument where sufficientrange of motion no longer exists.

By way of example, at each elevation value, a particular theoreticalrange of motion for pitch and roll is achievable. Thus, as describedabove, it is contemplated the range of motion in pitch or roll maydepend on the elevation value for which it is plotted. In other words,at a first elevation (see FIGS. 13-18 ), the hand-held portion may becapable of reaching a first range of pitch and roll values, and at asecond elevation (see FIGS. 19-20 ), the hand-held portion may becapable of reaching a second range of pitch and roll values, with thefirst range of pitch and roll values being different from the secondrange of pitch and roll values. This difference in range of motion atdifferent elevations is based on the kinematics of the actuator assemblyand the joints used to couple the plurality of actuators between thetool support and the hand-held portion.

Because the range of motion of the hand-held portion potentially differsat elevation values, the outer boundaries of the various two-dimensionalslice regions may also differ from one another and hence the shape andsize of the two-dimensional slice regions may different from oneanother. For example, certain two dimensional slice regions may besymmetric, while others may be asymmetric; certain dimensional sliceregions may be polygonal, while others may be circular, and so on. Asshow in FIGS. 19 and 20 , the two dimensional slice regions aretriangular in nature, whereas, in FIGS. 13-18 , the two-dimensionalslice regions are pentagonal in nature. More particularly, referringagain to FIGS. 13-18 and FIGS. 19-20 , among the plurality oftwo-dimensional regions that collectively define the range of motion ofthe hand-held portion, one of the two-dimensional regions correspond toa first range of motion in pitch and roll at a first elevation andanother one of the two-dimensional regions correspond to a second rangeof motion in pitch and roll at a second elevation.

To understand the relationship between the pose of the hand-held and thetheoretical range of motion in a scaled manner, one more positions ororientations of the hand-held portion may be modeled based on theplurality of two dimensional slice regions, in a polar coordinatesystem. The outer boundary of each two-dimensional region may be definedbased on at least four pairs of coordinates, such as four pairs ofcoordinates representing pitch and roll, but is often represented by aseries of lines, each having its own equation. More particularly, asmentioned above, the pose may include a pitch value, a roll value, anelevation value or values in other degrees of freedom. First, thetwo-dimensional region corresponding to the commanded pose of thehand-held portion is selected. In one example, this is done by selectingthe two-dimensional region of the theoretical range of motioncorresponding to the elevation value of the commanded pose of thehand-held portion.

The pitch value and the roll value corresponding to the elevation valuefor the commanded pose can be understood as a vector drawn in thetwo-dimensional slice region. This vector, referred to as the actualdeviation vector, extends from an origin of the two-dimensional regionto an endpoint defined by the pitch value and the roll value of thecommanded pose in Cartesian space. More generally, the actual deviationvector can be understood to extend from the origin of at least one ofthe plurality of two-dimensional regions to a point defined in the polarcoordinate system by the position of the hand-held portion in the seconddegree of freedom and the position of the hand-held portion in a thirddegree of freedom, with the first degree of freedom defining which ofthe plurality of two-dimensional regions is selected for plotting of theactual deviation vector. In certain examples, the end of the deviationvector may be characterized by one or more equations that define theportion of the boundary of the two-dimensional slice that wouldintersect the actual deviation vector if the actual deviation vector hadan infinite magnitude

The actual deviation vector exhibits a magnitude and a direction. InFIG. 14 , the actual deviation vector is labeled as ADV1, andcorresponds to a a roll value of x1, and a pitch value of y1,approximately 8 degrees in pitch and 14 degrees in roll. ADV1 has anangle theta2 of approximately 30 degrees and a magnitude of 16. In FIG.16 , the actual deviation vector is labeled as ADV2, and corresponds tox2, y2, which equates to −10 degrees in roll and −6 degrees in pitch.ADV2 has an angle theta4 of approximately 210 degrees and a magnitude of12. In FIG. 17 , the actual deviation vector is labeled as ADV3, andcorresponds to x3, y3, which relates to −4 degrees in roll and −2degrees in pitch. ADV3 has an angle theta5 of approximately 210 degreesand a magnitude of 5. In FIG. 20 , the actual deviation vector islabeled as ADV4 and corresponds to x4, and y4, approximately 12 degreesin roll and 4 degrees in pitch. ADV4 has an angle theta8 ofapproximately 30 degrees and a magnitude of 13.

Referring to FIGS. 13, 15, 18, and 19 , in certain implementations, thecontrol system further determines a range of motion vector (RMV1-4) or arange of motion line (RML1-RML4) with respect to the sametwo-dimensional slice region that was used to model the actual deviationvector, i.e., the same elevation. The length of the range of motionlines (RML1-4) represents the range of motion that is possible for thatelevation value with the particular combination of pitch and rollvalues, whereas the length of the range of motion vector represents therange of motion that is possible for that elevation value on one side ofthe origin with the particular combination of pitch and roll values.More particularly, the control system is configured to determine a rangeof motion line in the polar coordinate system based on the position ororientation of the hand-held portion in the first degree of freedom. Therange of motion line extending from the boundary point of atwo-dimensional region to a boundary point of the same two-dimensionalregion, at the opposite angle of the boundary point. In other words, therange of motion line can be understood as two line segments, the firsthaving a first angle and the second segment have a line segment at thefirst angle +180 degrees. In this manner, the first and second linesegments both extend from the same origin, and both extend from theorigin to points on the outer boundary of the two-dimensional slice. Thefirst angle is always equal to the angle of the deviation vector foreach calculation. Based on this composition, the range of motion line isalways colinear with the actual deviation vector, but not fullycoextensive with the actual deviation vector. The magnitude of the rangeof motion line may be computed in various ways. In one example, anintersection point between the range of motion line and one lines thatdefine the two-dimensional slice region. It should be understood thatthe range of motion line may be represented by an equation as well, andthe equations for the range of motion line and the lines that define theportion of the boundary region that intersects the range of motion canbe solved to determine the two sets of x, y values of the intersectionof the range of motion line and the two-dimensional slice region at eachend of the range of motion line. Based on these two sets of x y values,the magnitude of the range of motion line can be computed. The range ofmotion vector has an angle equal to the angle of the actual deviationvector. One segment of the range of motion line may consist of the rangeof motion vector.

In FIG. 13 , the range of motion vector is labeled as RMV1, andcorresponds to a pitch value of y5 and a roll value of x5, approximately10 degrees in pitch and 18 degrees in roll. RMV1 has an angle theta1 ofapproximately 30 degrees and a magnitude of 21. In FIG. 15 , the rangeof motion vector is labeled as RMV2, and corresponds to x3, y3, whichequates to −12 degrees in roll and −7 degrees in pitch. RMV2 has anangle theta3 of approximately 210 degrees and a magnitude of 14. In FIG.18 , the range of motion vector is labeled as RMV3, and corresponds tox9, x9, which relates to 18 degrees in roll and 12 degrees in pitch.RMV3 has an angle theta6 of approximately 30 degrees and a magnitude of22. In FIG. 19 , the range of motion vector is labeled as RMV4 andcorresponds to x11, y11, approximately 20 degrees in roll and 6 degreesin pitch. RMV4 has an angle theta7 of approximately 30 degrees and amagnitude of 21. RML1 (ending at x6, y6), RML2 (ending at x7, y7), RML3(ending at x10, y10), and RML4 (ending at x12, y12) are each larger thantheir respective RMV. However, as can be appreciated from the Figures,the magnitude of the RMLs is not necessary double the magnitude of theRMVs. This is because the two-dimensional regions are not necessarysymmetrical about their origin at each angle of the RMV. While thespecific examples described below refer to controlling the visualindicators based on a comparison of the magnitude of the range of motionvector and the magnitude of the actual deviation vector, it is alsocontemplated that the visual indicators may be controlled based on themagnitude (i.e., length) of the range of motion line.

To appropriately compare the range of motion line or vector and theactual deviation vector, the direction of the deviation vector must beequal to a direction of a segment of the range of motion line or angleof the deviation vector, in other words, angle theta for each must beequal to each other. In other words, the range of motion line or therange of motion vector is computed based on the direction of the actualdeviation vector Similarly, to appropriately compare magnitudes of thetwo vectors or compare magnitudes of the actual deviation vector and therange of motion line, range of motion line must extend through the sameorigin that the actual deviation vector extends from in thetwo-dimensional region and the range of motion vector must extend fromthe same origin that the actual deviation vector extends from. The rangeof motion line may be understood as extending to two boundary points ofthe two-dimensional region based on the position of the hand-heldportion in one or more degrees of freedom, whereas the range of motionvector may be understood as extending to a single boundary point of thetwo-dimensional region. The magnitude of the range of motion one may becomputed based the two-dimensional region and based on two pairs ofcoordinates defining the end of the range of motion; line on thetwo-dimensional region, i.e., the boundary points, whereas the magnitudeof the range of motion vector may be computed based on the origin of thetwo-dimensional region and based on a pair of coordinates defining theend of the range of motion vector on the two dimensional region, theboundary point.

Regarding FIGS. 13 and 14 , it should be understood that theta1 is equalto theta2, and the magnitude of ADV1 is smaller than RMV1. Bymathematically comparing the magnitude of RMV1 and ADV1, the controlsystem can approximate the percentage of range of motion remaining forthe hand-held portion at any given pose of the hand-held portionrelative to the closest range of motion boundary. For example, bydividing the magnitude of ADV1 by the magnitude of RMV1, it can beunderstood that approximately 22 percent range of motion remains for thehand-held portion at that pose of the hand-held portion relative to theclosest range of motion boundary. These magnitudes of the range ofmotion vectors and the actual deviation vectors can be used to controlthe visual indicators described throughout.

Regarding FIGS. 15 and 16 , it should be understood that theta3 is equalto theta4, and the magnitude of ADV2 is smaller than RMV2. Bymathematically comparing the magnitude of RMV2 and ADV2, the controlsystem can approximate the percentage of range of motion remaining forthe hand-held portion at any given pose of the hand-held portionrelative to the closest range of motion boundary. For example, bydividing the magnitude of ADV2 by the magnitude of RMV2, it can beunderstood that approximately 17 percent range of motion remains for thehand-held portion at that pose of the hand-held portion. Thesemagnitudes of the range of motion vectors and the actual deviationvectors can be used to control the visual indicators describedthroughout.

Regarding FIGS. 15 and 17 , it should be understood that theta3 is equalto theta5, and the magnitude of ADV3 is smaller than RMV2. Bymathematically comparing the magnitude of RMV2 and ADV3, the controlsystem can approximate the percentage of range of motion remaining forthe hand-held portion at any given pose of the hand-held portionrelative to the closest range of motion boundary. For example, bydividing the magnitude of ADV3 by the magnitude of RMV2, it can beunderstood that approximately 66 percent of the range of motion remainsfor the hand-held portion at that pose of the hand-held portion relativeto the closest range of motion boundary. These magnitudes of the rangeof motion vectors and the actual deviation vectors can be used tocontrol the visual indicators described throughout.

Regarding FIGS. 14 and 18 , it should be understood that theta2 is equalto theta6, and the magnitude of ADV1 is smaller than RMV3. Bymathematically comparing the magnitude of RMV3 and ADV1, the controlsystem can approximate the percentage of range of motion remaining forthe hand-held portion at any given pose of the hand-held portion. Forexample, by dividing the magnitude of ADV1 by the magnitude of RMV3, itcan be understood that approximately 26 percent of the range of motionremains for the hand-held portion at that pose of the hand-held portionrelative to the closest range of motion boundary. These magnitudes ofthe range of motion vectors and the actual deviation vectors can be usedto control the visual indicators described throughout. It should beappreciated that the origin of the deviation vectors for 13 and 14 aredifferent, which may result in a changing magnitude of each of thevectors.

The origin may be set for the actual deviation vector in a number ofdifferent ways. In one example, the origin may be set as the centroid ofthe two-dimensional region. Alternatively, the origin may set as a pointother than the centroid of the two-dimensional region, such as thegeometrical center. Alternatively still, the origin may be set to therange of motion in a particular degree of freedom to be unbalanced oneach side of the origin. For example, by comparing FIGS. 14 and FIGS. 18, relative to the pitch degree of freedom, there is the possibility ofgreater range of motion above the origin than below the origin. This mayresult in asymmetrically controlling the visual indicator to lead theuser to favor one side or the other side of the range of motion. This isbecause there is a greater likelihood that the user would be prompted tomove his or her hand down than up in FIG. 14 than compared to FIG. 18 .The same can be true in the roll degree of freedom. Such a configurationmay be advantageous if a user has a tendency to tilt or twist his or herhand a certain way, or based on the cut selected by the user. In otherwords, the control system may be operated to set the origin of theactual deviation vector based on which cut is elected to be made by theuser. Alternatively, the control system may present a user interfacethat allows the user to select a configuration that changes the origin.

Regarding FIGS. 19 and 20 , it should be understood that theta7 is equalto theta8, and the magnitude of ADV4 is smaller than RMV4. Bymathematically comparing the magnitude of RMV4 and ADV4, the controlsystem can approximate the percentage of range of motion remaining forthe hand-held portion at any given pose of the hand-held portionrelative to the closest range of motion boundary. For example, bydividing the magnitude of ADV4 by the magnitude of RMV4, it can beunderstood that approximately 60 percent of the range of motion remainsfor the hand-held portion at that pose of the hand-held portion relativeto the closest range of motion boundary. These magnitudes of the rangeof motion line and the actual deviation vectors can be used to controlthe visual indicators described throughout.

The control system is configured to control the visual indicator basedon the magnitude of the actual deviation vector, the magnitude of therange of motion vector, the direction of the actual deviation vector,the direction of the range of motion vector or combinations thereof.

Additionally, by isolating and comparing the x-components (correspondingto roll) and the y-components (corresponding to pitch) of the actualdeviation vector, the control system can also control the visualindicators based on the range of motion remaining in the pitch degree offreedom or the roll degree of freedom (or other degrees of freedom)independently. In other words, a pitch indicia of the visual indicatormay be based on the y-component of the actual deviation vector.Similarly, a roll indicia may be controlled based on the x-component ofthe actual deviation vector. Furthermore, an indicia that simultaneouslyshows pitch and roll, referred to herein as a pitch-roll indicia, may becontrolled on both components of the actual deviation vector.

Referring again to FIGS. 14, 16, and 17 , as an alternative tocontrolling the visual indicators based on aspects of the range ofmotion vector, the control system may also control the visual indicatorsbased on other computations of the range of motion. This alternativemethod is particularly useful in instances where a separate visualindicator is used and controlled for each degree of freedom. In thisalternative example, the range of motion in a particular degree offreedom is computed based on the pose of the hand-held portion (moreparticularly, based on the one or more degrees of freedom of thecommanded pose). For example, with reference to FIG. 14 , if thecommanded pose is defined as a particular roll, pitch and elevation, apitch range of motion is generated and a roll range of motion isgenerated based on aspects of the commanded pose. The commanded pose inpitch and roll is represented by x1, y1 (14 degrees in roll and 8degrees in pitch). The range of motion, based on this pose, in the pitchdegree of freedom, can be understood as the magnitude of the lineextending between on points P1 and P2. In other words, the magnitude ofthe range of motion available in the pitch degree of freedom is definedby the orientation in the roll degree of freedom at the commanded pose(at 14 degrees of roll, what degrees in pitch are available (−6 to +12.5degrees). This alternative method of representing the range of motion ina particular degree of freedom selects a range of motion for a degree offreedom (such as pitch) based on the pose in a different degree offreedom (roll in this example) and based on the Cartesian model of therange of motion.

Still with reference to FIG. 14 , as another example, the control systemmay determine the range of motion in roll based on the pose in pitch,such as the commanded pose. The commanded pose in pitch is 8 degrees.The range of motion in roll based on this pose can be understood as themagnitude of the line extending between points R1 and R2. In otherwords, at +8 degrees in pitch, the range of motion in roll can beunderstood to extend from −22 to +22 degrees.

With reference now to FIG. 16 , the commanded pose of the hand-heldportion is determined to be −10 degrees in roll and −6 degrees in pitch(see x2, y2). Based on the value of −10 degrees in the roll degree offreedom, the range of motion in the pitch degree freedom extends from+13 to −9 degrees, or a magnitude of 22 degrees (defined by themagnitude of the line extending from P3 to P4). Based on the value of −6degrees in in the pitch degree of freedom, the range of motion in theroll degree of freedom is computed to be −15 to +15, or 30 degrees(defined by the magnitude of the line extending from R3 to R4).

With reference to now to FIG. 17 , the commanded pose of the hand-heldportion is determined to be −4 degrees in roll and −2 degrees in pitch(see x3, y3). Based on the value of −4 degrees in the roll degree offreedom, the range of motion in the pitch degree freedom extends from+12.5 to −14 degrees, or a magnitude of 26.5 degrees (defined by themagnitude of the line extending from P5 to P6). Based on the value of −2degrees in in the pitch degree of freedom, the range of motion in theroll degree of freedom is computed to be −19 to +19, or 38 degrees(defined by the magnitude of the line extending from R5 to R6).

Furthermore, while it is described that the magnitude of the roll rangeof motion is based on the pitch component of the commanded pose, itshould be appreciated that the magnitude of the roll range of motioncould also be determined based on other components of the commandedpose, such as elevation, yaw, x-axis translation or y-axis translation.The same is true for the pitch range of motion, in that it should beappreciated that the magnitude of the pitch range of motion could alsobe determined based on other components of the commanded pose, such aselevation, yaw, x-axis translation or y-axis translation

As described above, the magnitude of the range of motion may bedetermined differently for different visual indicator configurations. Aswill be described below, for certain implementations of the visualindicators, particularly those that include a single indicia for eachdegree of freedom, the magnitude of the range of motion in a particulardegree of freedom may be determined based on the value of the degree offreedom for a different degree of freedom and based on the Cartesianmodel. In other implementations of the visual indicators, such as thearray of light sources, that indicate pitch and roll collectively, mayrely on the magnitude of the range of motion vector described above orbased on the magnitude of the range of motion line.

Referring to FIGS. 1, 21-24 and 26-27C, the visual indicator maycomprise one or display screens 300, 401, 500, 600, 700UI. Each displayscreen may take various forms.

Referring to FIG. 21 , the control system may further be configured tocontrol the display screen 300 to display a translation indicia 302based on the position of the hand-held portion in the first degree offreedom (a translation degree of freedom). The display screen mayfurther include translation reference object 304 sized to denote athreshold in the translation range. The translation indicia 302 may bepositioned within, or relative to, the translation reference object 304based on the position or orientation of the hand-held portion in thetranslation degree of freedom and a translation threshold value. Thetranslation threshold value may be based on a range of translationthreshold values, i.e., the translation threshold value may actuallyinclude an upper translation threshold value and a lower translationthreshold values. The range of translation thresholds may be based onthe Cartesian model representing the three-dimensional workspacedescribed above. In certain instances, the display screen 300 isconfigured to display two or more translation reference objects 304, atleast one translation reference object 304 located on each side of thedisplay screen 300. Each of the translation reference objects 304 mayinclude a translation indicia 302 based on the position of the hand-heldportion in a translation degree of freedom, such as the elevation degreeof freedom. In one example, if the position of the hand-held portion isdetermined to be 5 in the elevation degree of freedom (as determinedfrom the commanded pose), and the range of motion in the elevationdegree of freedom is determined to be +10 to −10, the translationindicia may be positioned at approximately 75% of the height of thetranslation reference object. In other words, the position of thetranslation indicia within the translation reference object provide fora scaled understand of the commanded elevation position relative to therange of motion available for elevation.

Referring to FIG. 22 , the control system may be configured to controlthe display screen 400 to display a roll indicia 402 based on acomponent of the magnitude of the actual deviator vector in the rolldegree of freedom and a magnitude of the range of motion in the rolldegree of freedom. As mentioned above, the magnitude of the range ofmotion in the roll degree of freedom may be based on a pitch componentof the commanded pose. Furthermore, the display screen 401 is configuredto display a roll reference object 404, wherein the roll indicia 402 ispositioned relative to the roll reference object based on thex-component of the actual deviation vector and the magnitude of therange of motion in the pitch degree of freedom. The roll referenceobject 404 may include a plurality of spatial annotations 406 positionedat prescribed locations about an arc, each spatial annotation 406identifying a known angle associated therewith, with each spatialannotation 406 thereby enabling a visual assessment of the roll of thehand-held portion relative to the tool support.

Referring to FIGS. 23 and 24 , the control system may further beconfigured to display a pitch-roll indicia 502, 602 based on themagnitude of the x-component and y-component of the actual deviationvector (pitch and roll components) and the magnitude of the range ofmotion in the roll degree of freedom and the magnitude of the range ofmotion in the pitch degree of freedom. In certain instances, thepitch-roll indicia 502, 602 is a 2-d representation of a 3-D virtualobject, the 2-D representation configured based on the magnitude anddirection of the actual deviation vector and the magnitude and directionof the range of motion line. The exemplary 3-D object is a polygon torepresent a saw blade, with the polygon having a front and a back, theback of the polygon is position opposite the front of the polygon withthe front or the back of the polygon being positioned based on themagnitude of the x-component and y-component of the actual deviationvector (pitch and roll components) and the magnitude of the range ofmotion in the roll degree of freedom and the magnitude of the range ofmotion in the pitch degree of freedom. In one implementation, thecontrol system may be configured to determine a y-component (such aspitch component) of the actual deviation vector and a magnitude of therange of motion of the hand-held portion in the pitch degree of freedomand display the pitch-roll indicia based on the y-component of theactual deviation vector and the magnitude of the pitch component of therange of motion. More particularly, the position of the 2-Drepresentation may be scaled to an appropriate position (vertically)within the display screen based on the ratio of these values Similarly,the control system may be configured to determine a x-component (such asthe roll component) of the actual deviation vector and a magnitude ofthe range of motion of the hand-held portion in the roll degree offreedom, and the display screen is configure configured to display the2-D representation may be scaled to an appropriate position(rotationally) based on the ratio of the x-component of actual deviationvector and the magnitude of the range of motion in the roll degree offreedom.

With respect to the left-most display 500 in FIG. 23 , the ratio of thepitch of the hand-held portion and the magnitude of the pitch range ofmotion indicates that the y-component of the actual deviation vector isnear the bottom of the range of motion (in the pitch-degree of freedom),and hence the front face of the pitch-roll indicia 502 is near thebottom of the screen. With the central display 502′ in FIG. 23 , thepitch of the hand-held portion is near the top-most range of motion inthe pitch degree of freedom and hence the front face pitch-roll indicia502 is near the top of the display. And with reference to the right-mostdisplay 502″ of FIG. 23 , the pitch component of the of the hand-heldportion is in the center of the range of motion in the pitch degree offreedom, And, hence the front face of the pitch-roll indicia is in thecenter of the display screen. For each of these, the virtual object isdisplayed such that what would be the rear face cannot be seen.

With respect to FIG. 24 , the pitch-roll indicia 602 is positioned onthe display screen 600 in a position that would indicate that the pitchcomponent of the commanded pose is in the lower half of the magnitude ofthe range of motion in the pitch degree of freedom. As can be seen, thecenter of the pitch range of motion is between the lower pitch limit #2and the upper pitch limit #1 (i.e., the median of the magnitude of thepitch range of motion). These upper and lower pitch limits maycorrespond to the outer bounds of the magnitude of the pitch range ofmotion

Referring now to FIGS. 27A-27C, the instrument is shown withe thehand-held portion and the tool support in three differentconfigurations. With respect to the FIGS. 27A-27C, each display screenshows roll indicia 702, elevation indicia 704, and a pitch-roll indicia706. FIG. 27A shows the state of the roll indicia 702, the elevationindicia 704, and the pitch-roll indicia 706 based on the hand-heldportion based on the hand-held portion having a deviated pitch and roll,and a centered elevation. More particularly, 27A shows the hand-heldportion being at the bottom left corner of the range of motion. FIG. 27Bshows the state of the roll indicia 702, the elevation indicia 704, andthe pitch-roll indicia 706 based on the hand-held portion having adeviated pitch and roll, and an off-center elevation. More particularly,FIG. 27B shows the pitch-roll indicia 706 corresponding to the hand-heldportion being at the top right corner of the range of motion. FIG. 27Cshows the state of the roll indicia 702, the elevation indicia 704, andthe pitch-roll indicia 706 based on the hand-held portion with adeviated pitch, and a desired position in the elevation degree offreedom.

In certain configurations, with reference to FIGS. 28-31, 33A, 34, 37,and 42B, the visual indicator include a plurality of light sources. Moreparticularly, with reference to FIGS. 28-30 , the visual indicator 800may include one or more light sources corresponding to the pitch androll degrees of freedom, known as the pitch-roll indicator 804, one ormore light sources corresponding to the translation degree of freedom(i.e., elevation), known as the translation visual indicator 802, and alight source 806 configured to indicate whether the hand-held portion iswithin a certain threshold of the home position in more than one degreeof freedom. The control system may be configured to control a state ofat least one of the plurality of light sources. The control system maycontrol the state of the plurality of light sources 802, 804, 806 basedon the magnitude of the actual deviation vector, the direction of theactual deviation vector, the magnitude of the range of motion vector, orthe magnitude of the range of motion line, the direction of the range ofmotion vector, or combinations thereof to simultaneously indicate to theuser one more desired changes in one or more of a pitch orientation, aroll orientation, and a translation position. Alternatively, asmentioned above, the visual indicator may include fewer or additionallight sources than described above to indicate desired changes indegrees of freedom other than elevation, pitch, and roll.

The state of the plurality of light sources 802, 804, 806 may includewhether at least one light source of the plurality of light sources ison or off; a frequency of a light pulse emitted by the at least onelight source; an intensity of the light emitted by the at least onelight source; a color of the at least one light source; or combinationsthereof. These states may be controlled via sending particular commandsto the light sources, or controlling the current, voltage, or acombination thereof supplied to the plurality of light sources.

The visual indicator may include the plurality of light sources arrangedin a particular manner with respect to one another to maximize deliveryof information to the surgeon in an intuitive manner. In oneconfiguration, at least three pitch-roll light sources 804 of theplurality of light sources are in a common plane with one another. Thismay allow for the surgeon to intuitively understand that the pitch androll light sources 804 represent the plane of the hand-held portion 16.While three light sources are mentioned here, any number of lightsources may be positioned in a common plane with one another, forexample, at least four, six, eight, ten, or twelve light sources may bepositioned in a common plane with one another. The at least three of thepitch-roll plurality of light sources 804 may be arranged to surround acentral axis 808, collectively referred to as the array 805. In otherwords, the plurality of light sources in the array may be radiallyspaced an equidistant amount from a central point to give the appearanceof a circle, or more generally, the plurality of lights may be arrangedto circumscribe the central axis 808.

As described above, the circumscribing array 805 of light sources may becontrolled by the control system based on the magnitude of the actualdeviation vector. The circumscribing array 805 of light sources may alsobe controlled based on the magnitude of the range of motion vector. Inother words, the control system may compare the magnitude of actualdeviation vector the magnitude of range of motion vector, and based onthe comparison, illuminate one or more light sources 804 that make upthe array 805. The magnitude of the range of motion vector may bedivided into predetermined equal fractions, such as quadrants, thirds,or some other fixed percentage intervals. These fractions of the ofmagnitude of the range of motion vector may be used to generate one ormore deviation threshold values, which may facilitate control of theplurality of light sources. For example, the deviation threshold valuemay include an upper deviation threshold value and a lower deviationthreshold value. However, the magnitude may be used to generate anynumber of thresholds, including thresholds in addition to the upperdeviation threshold and the lower deviation threshold value. Inaddition, the magnitude may be used to generate a set of nested rangesof threshold values, for example within 20% of the center of themagnitude of the range of motion vector may be a first nested range andwithin 80% of the center of the magnitude of the range of motion vector.

Th upper and lower deviation threshold values or ranges may be set basedon a position or orientation in a particular degree of freedom that isdeemed desirable. More particularly, with respect to pitch, for example,the lower lower nested range may be set to the median 20% of the rangeof motion (corresponding the 20% of magnitude of the range of motionvector). In other words, if the range of motion in pitch is −10 degreesto 10 degrees, the lower deviation threshold value may be set to −2 to+2 degrees. If the pitch component of the actual deviation vector iswithin the −2 to the +2 degree range, the control system may control thearray 805 to present a particular pattern of illumination, such as alllight sources being on, all light sources being off, or the lightsources may be controlled to illuminate a particular color. With respectto the roll degree of freedom, the lower nested range may be set to themedian 20% of the range of motion in the roll degree of freedom. Inother words, if the range of motion in roll is −10 degrees to 10degrees, the lower nested range may be set to −2 to +2 degrees. If theroll component of the actual deviation vector is within the −2 to the +2degree range, the control system may control the array 805 to present aparticular pattern of illumination, such as all light sources being on,all light sources being off, or all light sources controlled toilluminate a particular color. It is also contemplated that the array805 may be controlled by the control system based on the lower deviationvalue ranges for more than one degree of freedom simultaneously. Inother words, the control system may control the array 805 based on thepitch and the roll and the nested ranges corresponding to pitch androll. Accordingly, the array may only present a particular pattern, suchas all lights on or all lights off, if both the pitch component and rollcomponent of the commanded pose are within the lower nested rangevalues. The array may similarly be controlled based on whether such asall lights on or all lights off, if both the pitch component and rollcomponent of the commanded pose are within the upper set of nested rangevalues, or if the pitch and the roll component of the commanded pose areoutside of both the lower set of nested range values and the upper setof nested range values.

Referring to FIG. 25 , a schematic view of the array 805 of the visualindicator 800 is depicted. The control system may be further configuredto identify a root light source 810 in the circumscribing array 805 oflight sources. This may be computed based on a direction of the actualdeviation vector. The root light source 810 may be the pitch-roll lightsource 804 that is closest to the angle of the deviation vector. Theroot light source 810 may be designated a real light source or a virtuallight source. If it is a virtual light source, then another step isrequired which is identifying which real light source is closest to thevirtual light source. By modeling with real and virtual light sources,the algorithm can be scaled depending on the mechanical configurationsof the light array (the same algorithm can be applied to all differentspatial configurations of LEDs). In FIG. 25 , for simplicity, it will beassumed that all pitch-roll light sources 804 are real light sources.Because theta of the actual deviation vector is closest to the anglethat corresponds to the second light source clockwise from the uppermost light source, it is deemed the root light source 810.

The control system may be further configured to identify at least twoneighboring light sources 812 that are adjacent the root light source810 on a first side and a second side, i.e., on the right and left ofthe root light source 810. Once the neighboring light sources 812 areidentified, the control system may be configured to control a state ofthe at least two neighboring light sources based on the magnitude of theactual deviation vector and the magnitude of the range of motion vector.The state of the two neighboring light sources 812 may be whether the atleast two neighboring light sources are on or off. Alternatively, thecontrol system may control the frequency of a light pulse emitted by theat least two neighboring light sources; an intensity of the lightemitted by the at least two neighboring light sources; a color of the atleast two neighboring light sources; or combinations thereof. Theneighboring light sources 812 may include a light source in theclockwise direction relative to the root light source, and a lightsource in the counter-clockwise direction relative to the root lightsource in the array 805. In one example, if the range of motion is pitchis from −10 to +10 (derived from the range of motion vector), and thepitch value (i.e., the y-component of the deviation vector) is 8,outside of a nested range of −4 to +4), the control system mayilluminate the neighboring light sources 812. If the range of motion inpitch is −10 to +10, the nested range is −4 to +4 in pitch, and thepitch component of the commanded pose is 2, which is within the range,the control system may not illuminate the neighboring light sources 812.It should be appreciated that a similar control may be employed for theother degrees of freedom, particularly roll.

In certain implementations, the control system may further be designedto identify an additional group of neighboring light sources ('thesecondary neighboring light sources' 814) that are adjacent to theneighboring light sources 812 described above ('the primary neighboringlight sources'). The state of this additional group of neighboring lightsources 814 may be further controlled based on the magnitude of theactual deviation vector and the magnitude of the range of motion vector.For example, it is contemplated that control system may control thestate of the primary neighboring light sources 812 and the secondaryneighboring light sources 814 based on comparison to nest ed ranges.More particularly, the control system may turn on the primaryneighboring light sources 812 but not the secondary neighboring lightsources 814 if the magnitude of the actual deviation vector within aninner set of ranges. Furthermore, the control system may turn on thesecondary neighboring light sources 814 and the primary neighboringlight sources 812 if the magnitude of the actual deviation vector isoutside an inner nested range but within an outer nested range. Itshould be appreciated that the secondary neighboring light sources 814may include any number of light sources other than the root light source810 and the primary neighboring light sources 812. For example, thesecondary neighboring light sources 814 could include the completeremainder of pitch-roll light sources 804 in the circumscribing array805. In other words, it should be appreciated that when the root lightsource 810, the primary neighboring light sources 812, and the secondaryneighboring light sources 814 are all illuminated, all of the lightsources in the circumscribing array 805 may be illuminated. Furthermore,it is contemplated that the control system could be configured toidentify yet another group of neighboring light sources (‘the tertiaryneighboring light sources’ 816), and the control system could controlthe tertiary neighboring light sources 816 in a similar manner, i.e.,with a third or fourth nested range. It is also contemplated, theprimary and secondary neighboring light sources may each independentlyinclude any number of light sources, but typically include a symmetricalnumber of light sources in the counter clockwise and clockwise directionrelative to the root light source 810.

Referring again to FIG. 28 , the visual indicator 800 may also include atranslation visual indicator 802, which may be controlled differentlyfrom the circumscribing array 805. The control system may control astate of the light source associated with the translation visualindicator 802 based on the determined translation value and one or moretranslation threshold values or translation ranges. The translationthreshold values or translation ranges, including nested translationranges, may be fixed intervals or portions of the magnitude of thetranslation range of motion. The determined translation value is theposition of the hand-held portion in the translation degree of freedom,which may be determined based on the commanded pose. The translationvisual indicator 802 may include a plurality of light sources. Each ofthe light sources may correspond to one or more segments 803 a, 803 b,of the translation visual indicator. As such, the translation visualindicator 802 may include a first segment, a second segment, andoptionally additional segments, each of the segments including one ormore light sources. The control system may control a state of the lightsources corresponding to the first segment 803 a, the second segment 803b, and other segments to indicate to the user to change the translationposition of the hand-held portion. In one configuration, the firstsegment and the second segment are on opposite sides of a midline M ofthe translation visual indicator 802. In such an implementation, thecontrol system is configured to illuminate the light sourcescorresponding to the first segment 803 a or the second segment 803 btoindicate a direction of desired movement of the hand-held portion.

The first 803 a and second segments 803 bof the translation visualindicator 802 may be aligned on an axis 808. The axis of the translationvisual indicator 802 may be perpendicular to a plane defined by the toolsupport 18 or the tool 20. At least a portion of the translation visualindicator 802 may be surrounded by the circumscribing array 805 of lightsources. In addition, the axis of the translation visual indicator 802may be perpendicular to a plane defined by the circumscribing array 805of light sources. The control system may be further configured toidentify a root translation light source of those light sourcesassociated with the translation visual indicator.

However, the root translation light source is not identified using theangle of the deviation vector, but rather based on the translation valueand based on the one or more translation threshold values. The controlsystem may control the state of the light segments corresponding to thetranslation indicator based on the translation component of thecommanded pose and the translation threshold value or the nestedtranslation ranges. Each of the nested translation ranges may include anupper translation threshold value and a lower translation thresholdvalue.

With respect to FIGS. 29A-29G, the statue of the visual indicators aredescribed with reference to exemplary spatial configurations aredescribed. FIG. 29A represents that that the hand-held portion isaligned with the tool support in all degrees of freedom. This isdepicted on the visual indicator 800 by illuminating light segment 803 cof the translation visual indicator, the median light segment, whichindicates that the hand-held portion 16 is within the approximate centerof the range of motion in the pitch degree of freedom (or within theinnermost translation nested range). The light source 806 is alsoilluminated because the hand-held portion 16 is within the desired rangeof motion for pitch and roll degrees of freedom (the pitch component ofthe hand-held portion is within the innermost pitch nested range and theroll component of the hand-held portion is within the innermost rollnested range.). Furthermore, all light sources within the array 805,such as light sources 804 a-804 h are illuminated, to indicate that thehand-held portion is generally aligned with the tool support to desiredrange of motion in the pitch and roll degrees of freedom.

With respect to FIG. 29B, the hand-held portion is pitched relative tothe tool support, and the user is desired to tilt the hand-held portionforward to reach the desired range of motion. In this instance, becauseonly a change in pitch is desired, the light segment 803 c of thetranslation visual indicator is illuminated. Furthermore, the root lightsource 804a is illuminated, because a change in pitch and only pitch isdesired (actual deviation vector of approximately 0 degrees). Becausethe pitch of the hand-held portion exceeds a first threshold, two of theneighboring light sources are also illuminated light segments 804 b, 804h.

With respect to FIG. 29C, the user is desired to tilt the hand-heldportion backwards in the pitch direction and to raise the hand-heldportion upwards. To address the raising of the hand-held portion, lightsource 803 e of the translation indicator is illuminated because thetranslation is near the lowermost translation threshold value. Toaddress the change in pitch desired, the root light source is identifiedas 804 e (actual deviation vector having an angle of approximately 180degrees). Based on the magnitude of the change in pitch desired,neighboring light sources 804 d and 804 f are also illuminated.

With respect to FIG. 29D, the user is desired to twist the hand-heldportion clockwise in the roll degree of freedom and no change inelevation is required. This is depicted on the visual indicator 800 byilluminating light segment 803 c of the translation visual indicator,which indicates that the hand-held portion 16 is within the approximatecenter of the range of motion in the pitch degree of freedom. The rootlight source 804 g is identified and illuminated (actual deviationvector having a direction of approximately 270 degrees). Based on thedegree of roll movement required, neighboring pitch-roll light sources804 h and 804 f are also illuminated.

With respect to FIG. 29E, the user is desired to twist the hand-heldportion counter-clockwise in the roll degree of freedom. To address theraising of the hand-held portion, light source 803 e of the translationindicator is illuminated because the translation is near the lowermosttranslation threshold value. The root light source 804 c is identifiedand illuminated (actual deviation vector having a direction ofapproximately 90 degrees). Based on the degree of roll movementrequired, light sources 804 b and 804 d are also illuminated, which canbe considered the neighboring light sources or neighboring lightsegments.

With respect to FIG. 29F, the user is desired to raise the hand-heldportion up, i.e., change the elevation, and no change is desired in thepitch and roll degrees of freedom. To address the raising of thehand-held portion, light source 803 e of the translation indicator isilluminated because the translation is near the lowermost translationthreshold value, or is outside, on the lower side, of the outermosttranslation nested range. The light source 806 is also illuminatedbecause the pitch and roll components of the commanded pose of thehand-held portion 16 is within the inner most nested ranges for pitchand roll degrees of freedom. Furthermore, all light sources within thearray 805, such as light sources 804 a-804 h are illuminated, toindicate that the hand-held portion is generally aligned with the toolsupport to desired range of motion in the pitch and roll degrees offreedom.

With respect to FIG. 29G, the user is desired to lower the hand-heldportion down, i.e., change the elevation, and no change is desired inthe pitch and roll degrees of freedom. To address the lowering of thehand-held portion, segment 803 a of the translation indicator isilluminated because the translation is near the uppermost translationthreshold value. The light source 806 is also illuminated because thehand-held portion 16 is within the desired range of motion for pitch androll degrees of freedom. Furthermore, all light sources within the array805, such as light sources 804 a-804 h are illuminated, to indicate thatthe hand-held portion is generally aligned with the tool support todesired range of motion in the pitch and roll degrees of freedom.

With respect to FIG. 30A-30E, the translation visual indicator 802 isfurther described. The translation visual indicator 802 can include aplurality of light segments 803 a-803 e. Each light segment may beassociated with one or more light sources. The translation thresholdvalue(s) may comprise a range of translation threshold values. The rangeof the translation threshold values may be based on the Cartesian modelrepresenting the three-dimensional workspace of the tool supportrelative to the hand-held portion. For example, if the translation valueof the hand-held portion is 5, and the range of motion in translation is−10 to +10, the control system would identify the second segment (803 b)of the five segment shown as part of the translation indicator (See FIG.30B). If the translation value is 10, the upper most light source (803a) in the translation visual indicator 802 may be illuminated (See FIG.30A). One or more of the light segments 803 a-803 e may be configured toemit a different color than the other light segments. For example, theupper most and lower most light segments (803 a) and 803(e) may beconfigured to emit the same color, whereas the central light segment 803c may be configured to emit a different color from the upper most andlower most light segments. Further still, the intermediate lightsegments (803 band 803 d) may be configured to emit a third color light.By emitting different color lights depending on the translation value,the user can understand how close he or she is to the range of motionlimits in translation. FIG. 30A indicates that the elevation value isclose to the top of the range of motion limit for elevation. FIG. 30Bindicates that the elevation value is in between the top of the range ofmotion t threshold (which would cause illumination of 803 a), and acentral range of motion threshold (which would cause illumination of 803c ). FIG. 30C has 803 c illuminated, which indicates that the elevationvalue is between a central range of motion threshold range. FIG. 30D isthe inverse of FIG. 30B (with segment 803 d illuminated), and FIG. 30Eis the inverse of FIG. 30A, with 803 e illuminated.

FIG. 31 is another representation of a visual indicator 900. The centralpost 902 may function like the translation visual indicator 802described above, and include a plurality of segments controlled asdescribed above with respect to FIGS. 30A-30E. The visual indicator 900may further include the array 905, which may include a plurality oflight sources. The array 905 may function as described above withrespect to the array 805 and may include a plurality of light sourcessimilar to array 805.

Importantly, based on the visual indicators described above, an operatorof the hand-held robotic system can visually understand whether theblade support 18 has a desired range of motion relative to the hand-heldportion 16. Particularly, when in the home position, the amount ofadjustability of the actuators 21, 22, 23 is maximized to keep the tool20 at a desired pose. Various levels of adjustment are possibledepending on the particular geometry and configuration of the instrument14. In some examples, when all the actuators 21, 22, 23 are in theirhome positions, the tool 20 may be adjusted in pitch orientation about+/−18° relative to the home position, assuming zero changes in the rollorientation and no z-axis translation. In some examples, when all theactuators 21, 22, 23 are in their home positions, the tool 20 may beadjusted in roll orientation about +/−33° relative to the home position,assuming zero changes in the pitch orientation and no z-axistranslation. In some examples, when all the actuators 21, 22, 23 are intheir home positions, the tool 20 may be adjusted in z-axis translationabout +/−0.37 inches relative to the home position, assuming zerochanges in the pitch orientation and roll orientation. The tool 20 maybe adjusted in pitch, roll, and z-axis translation simultaneously,sequentially, or combinations thereof during operation.

FIGS. 32A-C shows a representations of the display screen in whichindicia provides intuitive information to the user as to the pitch androll of the hand-held portion, the or elevation of the hand-heldportion. The indicia provided may be indicative of the plane of thehand-held portion relative to the desired cutting plane previouslyintroduced. The indicia may include a circle or other markingrepresentative of desired cutting plane. The circle may be static. Theindicia may further include an “X” or other type of marking that ismovable relative to the circle. Should the plane of the hand-heldportion deviate from the desired cutting plane in pitch, roll, or both,the X may be displayed outside of the circle. For example, deviations inpitch may include the X being displayed above or below the circle, anddeviations in roll may include the X being displayed to the right orleft of the circle. With the above convention, FIG. 32B shows the planeof the hand-held portion being angled upwardly relative to the desiredcutting plane and rolled to the left of the desired cutting plane. FIG.32C shows the deviation to be less than that of FIG. 32B. The indiciamay also incorporate the z-axis position of the hand-held portionrelative to the desired cutting plane. In certain implementations, athickness of the circle may be altered based on the z-axis position ofthe hand-held portion relative to desired plane. For example, as thehand-held portion is moved upwardly or downwardly, the thickness of thecircle increases, as shown in FIG. 32B. The circle may increase inthickness to a predetermined maximum, or be completely filled in uponthe hand-held portion reaching a certain pose relative to the desiredcutting plane. The display may also provide for a visual working zonewith the indicia superimposed on the visual working zone.

FIG. 33A shows the indicia being displayed on an array of LED lights,for example, a five-by-five array. The array is shown as beingintegrated into the instrument, but may alternatively be shown on thedisplay previously introduced. The selective lighting of the LEDs lightsmay be such that, when the pitch, roll, and z-axis position of thehand-held portion is correct or at a desired position, a single,centered LED light of the array is illuminated. Otherwise, theilluminated LED lights provide intuitive information as to which one ormore of aspects of the pose of the hand-held portion is incorrect.Deviations in pitch and the roll of the hand-held portion may be shownby less than a completed square of the LED lights being illuminated.Further, deviations in the pitch and the roll of the hand-held portionmay be shown by the illuminated LED lights not being centered on thearray. With the above convention, FIG. 33A(1) show the hand-held portiondeviating in one of pitch and roll. In other words, the less than acomplete square of the LEDs is illuminated, however the would-becompleted square (if the pitch or the roll was correct) is centered onthe array. Further, the absence of the lower-right corner of the squareindicates to the user that the hand-held portion needs to be generallyadjusted in the lower-right direction to rectify the pitch, the roll, orboth. FIG. 33A(2-3) shows the hand-held portion deviating in both ofpitch and roll. Not only is less than a complete square of the LEDsilluminated, but also the illuminated LEDs of the would-be completedsquare are not centered on the array. In FIG. 33A(4), the pitch and theroll of the hand-held portion being correct, but the hand-held portion16 is deviated in the z-axis or elevation. As the instrument 14 is movedupwardly or downwardly and the hand-held portion approaches the desiredplane, the size of the square becomes smaller, as shown incrementally in33 a (4-6). FIG. 33A(6) shows the single, centered LED light of thearray illuminated, indicative of the when the pitch, roll, and z-axisposition of the hand-held portion being correct, as mentioned.

FIG. 33B utilizes a similar arrangement with a progressivelyilluminating circle as opposed to a square array. Deviations in pitchand the roll of the hand-held portion may be shown by less than acompleted circle being illuminated. FIG. 33B(1) of lower-left arc of thecircle being absent indicates to the user that the hand-held portionneeds to be generally adjusted in the lower-left direction to rectifythe pitch, the roll, or both. The z-axis or elevation may be indicatedby a position of a dot or other marking along a vertical linebifurcating the circle. Thus, FIG. 33B(2) shows the pitch and the rollof the hand-held portion being correct, as the circle is illuminated,but deviating in the z-axis, as the dot is not centered on the verticalline. As the hand-held portion is moved upwardly or downwardly, the dotmoves towards the center of the circle. FIG. 33B(3) shows the circlebeing illuminated and the dot centered along the vertical line withinthe circle, indicative of when the pitch, roll, and z-axis position ofthe hand-held portion being correct.

Referring now to FIG. 34 , the visual indicator may include a firstvisual indicator 1000′, a second visual indicator 1000″ a third visualindicator 1000′″, and a fourth visual indicator 1000″″. In the versionshown, each of the visual indicators 1000, 1000′, 1000″, 1000′″ includeone or more illumination sources coupled to the control system. In someversions, the illumination sources comprise one or more LEDs which canbe illuminated with different intensities/colors. The visual indicators1000, 1000′, 1000″, 1000′″ shown in FIG. 34 may be post-like instructure and extend upwardly from an upper surface of the tool support18. The visual indicators 1000, 1000′, 1000″, 1000′″ may be provided ina rectangular arrangement, as shown, or a square or other suitablearrangement. The color of the visual indicators 1000, 1000′, 1000″,1000′″, and more particularly differences in color between the visualindicators 1000, 1000′, 1000″, 1000′″ may be indicative of the pitch androll of the hand-held portion relative to the desired plane. Forexample, the distal two of the visual indicators 1000, 1000′, 1000″,1000′″ being at least predominately yellow and the proximal two of thevisual indicators 1000, 1000′, 1000″, 1000′″ being at leastpredominately red may be indicative of deviation in pitch relative tothe desired cutting plan Likewise, the left two of the visual indicators1000, 1000′, 1000″, 1000′″ being at least predominately yellow and theright two of the visual indicators 1000, 1000′, 1000″, 1000′″ being atleast predominately red may be indicative of deviation in roll relativeto the cutting plane. In other words, causing the colors of all of thevisual indicators 1000, 1000′, 1000″, 1000′″ to be the same, mayindicate that the orientation of the hand-held portion relative to thedesired cutting plane is correct. It is contemplated that less than fourof the visual indicators 1000, 1000′, 1000″, 1000′″ may be illuminatedto indicate deviation in pitch, roll, or both. The color (notnecessarily the differences in color) of visual indicators 1000, 1000′,1000″, 1000′″ may be indicative of the z-axis position relative to thedesired cutting plane. For example, the visual indicators 1000, 1000′,1000″, 1000′″ being red or yellow may be indicative of deviation in thez-axis position relative to the desired cutting plane, and the visualindicators 1000, 1000′, 1000″, 1000′″ being green may be indicative ofthe hand-held portion being in the desired position. Taken together,each of the visual indicators 1000, 1000′, 1000″, 1000′″ being the samecolor, namely green, may be representative of hand-held portion beingcorrect in pitch, roll, and z-axis position.

FIGS. 35A, 35B, and 35C each represent a display screen with a verticalline with a dot to be centered indicative of correct z-axis position.The indicia of FIG. 35A and 35B include a horizontal line intersectingthe vertical line at a center point, and an articulate line intersectingthe center point. The indicia may further include additional dots ormarkings indicative of position in pitch and roll relative to thedesired cutting plane. More particularly, a horizontal position of thedot on the horizontal line may be representative of pitch relative tothe desired cutting plane, and a position of the dot on the arcuate linemay be representative of roll relative to the desired cutting plane. Theuse of the arcuate line may be particularly intuitive given themovements resulting in deviating in roll; i.e., rotation about thex-axis. When the pitch, roll, and z-axis position of the hand-heldportion are correct, the dots converge on the intersection point. FIG.35A is representative of the hand-held portion being off in pitch, roll,and z-axis position. The deviation in roll is greater than the deviationin pitch, as the dot on the arcuate line is farther from theintersection point than the dot on the horizontal line. FIG. 35B isrepresentative of the pitch and the roll of the hand-held portion beingcorrect, but the hand-held portion being deviating in z-axis position.FIG. 35C is representative of the hand-held portion being correct inpitch, roll, and z-axis position, as the indicia appears as a singulardot at the intersection point.

FIGS. 36A-36C utilizes crosshairs to be representative of any deviationpitch, roll, and z-axis position relative to the desired cutting plane.A horizonal line of the crosshairs may be representative of pitch, and avertical line of the crosshairs may be representative of roll. Anintersection of the horizontal and vertical lines may be representativeof the z-axis position relative to an origin, for example, a center ofthe dashed box shown in FIG. 36A-36C. A progressively thickening one orboth of the horizontal and vertical lines may be indicative of deviationin pitch. Thus, FIG. 36A is representative of the hand-held portiondeviating in pitch and roll, as the vertical line of the crosshairs isin perspective and the crosshairs are rotated. FIG. 36B is furtherrepresentative of the hand-held portion deviating in z-axis position, asthe crosshairs are not centered on within the box. FIG. 36B isrepresentative of the hand-held portion being correct in pitch and roll,but the hand-held portion being deviated in z-axis position. FIG. 36C isrepresentative of the hand-held portion being correct in pitch, roll,and z-axis position. FIG. 36C also shows the box transforming with thehand-held portion being in the desired position in all controlleddegrees of freedom.

Referring to FIG. 37 , the visual indicator 1100 may include a firstvisual indicator 1102, a second visual indicator 1104, and a thirdvisual indicator 1106. The visual indicators 1102, 1104, 1106 of theimplementation shown are spherical-shaped LEDs coupled to the toolsupport and arranged linearly in a front-to-back fashion. The visualindicator 1100 may include a fourth visual indicator 1108 and a fifthvisual indicator 1110. The visual indicators 1108, 1110 of theimplementation shown are spherical-shaped LEDs coupled to the toolsupport, and are relatively smaller in diameter than that of the first,second, and third visual indicators 1102, 1104, 1106. The visualindicators 1102, 1104, 1106, 1108, 1110 may be configured to illuminatein a single color, for example, white, blue, grey, black, etc. Thevisual indicators 1102, 1104, 1106 may be directed to showing pitch andz-axis position of the hand-held portion relative to the desired cuttingplane, however other schemes using combinations of the visual indicators1102, 1104, 1106 are contemplated. The fourth and fifth visualindicators 1108, 1110 may be directed to showing roll of the hand-heldportion relative to the desired cutting plane, and thus positionedopposite the row of the first, second, and third visual indicators 1102,1104, 1106. Thus, illumination of the fourth visual indicator 1108positioned to the left of the first, second, and third visual indicators1102, 1104, 1106 with a certain color may be indicative ofcounterclockwise roll, and illumination of the fifth visual indicator1110 positioned to the right of the of the first, second, and thirdvisual indicators 1102, 1104, 1106 with a certain color may beindicative of clockwise roll. For the first, second, and third visualindicators 1102, 1104, 1106, illuminating one or more with certaincolors may be indicative of deviation in pitch, elevation, or both. Inone example, the hand-held portion may be manipulated until theforwardmost visual indicator 1102 is blue, and the second and thirdvisual indicators 1104, 1106 are black, thereby creating a single focalpoint for the user.

Referring now to FIG. 38 , the visual indicator 1200 may be mechanicalin form. In particular, the visual indicator 1200 uses alignmentfeatures on each of the hand-held portion 16 of the instrument 14 andthe tool support 18 of the instrument 14. The guidance array 1200 givesthe user visual feedback as to how the tool support 18 is positionedrelative to the hand-held portion 16 in an intuitive, familiar manner.In instances where the instrument 14 is a sagittal saw with the tool 20being a saw blade being oriented parallel to the ground, the features tobe described on the hand-held portion 16 may be on the same plane asthat of the tool 20 when the instrument 14 is at the nominal or “home”position. A leveler 1210 is coupled to the hand-held portion 16. Theleveler 1210 may include two plates 1212 separated by a recess 1214 orvoid. The plates 1212 are arranged coplanar to one another. The leveler1210 is coupled to the hand-held portion 16 such that, when the tool 20is at the home position, the tool 20 is parallel to the plates 1212. Inone example, the tool 20 may be coplanar with the plates 1212. Deviationin pitch and roll is readily ascertainable visually based on therelative orientation of the tool 20 to the plates 1212 of the leveler1210.

FIG. 39 shows another implementation of the visual indicator 1300 inwhich the leveler 1310 is coupled to the hand-held portion 16. Theleveler 1310 includes an arm 1312 coupled to the hand-held portion 16extending to a sight 1314 adjacent the tool support 18. The sight 1314may be an opening with crosshairs disposed about the opening. A beacon1316 may be coupled to the tool support 18 and arranged to be alignedwith the sight 1314 when the tool 20 is at the home position. The beacon1316 may also include crosshairs configured to be aligned to thecrosshairs of the sight 1314. It is appreciated that as the tool 20 andthe tool support 18 move relative to the hand-held portion 16 duringoperation of the instrument 14, the beacon 1316 moves relative to thesight 1314. With the instrument 14 maintaining the desired cutting planeas described, the user may manipulate the hand-held portion 16 in amanner to align the beacon 1316 with the sight 1314.

FIG. 40 show another schematic representation of the instrument 14 withanother implementation of the visual indicator 1400. The visualindicator 1400 includes at least one arm 1402 coupled to the hand-heldportion 16. The illustrated implementation includes a plurality of arms1402, optionally arranged equiangularly in a star-like pattern. Thevisual indicator 1400 includes at least one fork 1408 coupled to thetool support 18, and the illustrated implementation includes five forks1408 at the end of other arms 1404 arranged equiangularly in a star-likepattern complementary to the star-like pattern of the arms 222. At theend of each arm 1402 is a geometry 1406, for example a sphere,configured to be situated between the tines of the fork 1408 when thetool 20 is at the home position. More particularly, the geometries 1406may be coplanar with and equally spaced from opposing tines of the fork1408 when the tool 20 is at the home position. Again, the tool 20 andthe tool support 18 move relative to the hand-held portion 16 duringoperation of the instrument 14. The geometries 1406 move relative theforks 1408. The lack of alignment is readily apparent visually to theuser, and the user may manipulate the hand-held portion 16 in a mannerto realign the geometries 1406 with the forks 1408.

Referring to FIG. 41 , another schematic representation of theinstrument 14 with a visual indicator 1500 in which a window 1502 isdisposed within the hand-held portion 16 adjacent to the tool support18. More specifically, a proximal end of the tool support 18 is visiblethrough the window 1502. The hand-held portion 16 and the proximal end230 of the tool support 18 may include complementary markings configuredto be aligned when the tool 20 is in the home position. The marking onthe proximal end of the tool support 18 may be a horizontal line, andthe marking on the hand-held portion 16 being opposing projectionsadjacent the window 1502. With the tool 20 in the home position, thehorizontal line and the opposing projections are coplanar. Should thetool 20 and the tool support 18 move relative to the hand-held portion16, the complementary markings are no longer in alignment.

Referring to FIG. 42A, another exemplary visual indicator 1600 is shownon a display screen. This includes similar translation indicia 1602 asdescribed above, with a different visualization for pitch and rollindicia 1604. The circles and cross-hairs may each move relative to oneanother based on the pitch value, roll value, or both, and the angle ofthe actual deviation vector. Similarly, it is contemplated that theposition of the circles or crosshairs may be controlled based on themagnitude, direction, or both, of the actual deviation vector or therange of motion vector.

Referring to FIG. 42B, the visual indicator 1700 may include threelinear arrangement of visual indicators 1702, 1704, 1706 intersectingone another. The color of each segment of the visual indicators, andmore particularly differences in color between the visual indicators maybe indicative of the pitch and roll of the tool 20 relative to thedesired cutting plane. The plurality of light sources may be controlledin a manner described above with respect to FIGS. 29 and 30 . The visualindicator 1700 may be coupled to the tool support.

Referring to FIG. 42C, another exemplary visual indicator 1800 is shown.The position of the cross-hair may change based on the pitch, the roll,or both of the hand-held portion. The position of the cross-hair may becontrolled in the same manner as the pitch-roll indicia described abovewith respect to FIGS. 24, 26, and 27 .

The instrument controller 28 may switch enable the visual indicatorbased on an input signal, such as activation of an input device (e.g.footswitch, trigger, mouse click or touch screen press on navigation UI,38, etc.). Alternatively, the instrument controller 28 may be configuredenable the visual indicator based on the position of the tool 20 and theposition of a reference location of bone in a known coordinate system,such as patient trackers 54, 56. A reference location may be a point,surface, or volume in the coordinate system used to locate theinstrument 14 relative a target state, such as a target object. In oneparticular implementation, the reference location is a planned entry ofthe bone. For example, the reference location may be a surface of abone, a point within a bone, an imaginary or virtual point within theknown coordinate system, a volume in the coordinate system, or acombination thereof. The position or orientation of the referencelocation is known with respect to the patient tracker throughregistration and suitable planning steps. The instrument controller 28may switch modes or operate differently based on a distance parametercomputed between two objects, such as a distance between the tool and areference location. A distance parameter may be a distance (e.g. how farapart two objects are), magnitude (the direction of the distancerelative to one object), or both. In some examples, the instrumentcontroller 28 may switch modes when the distance parameter has adirection away from bone and a magnitude greater than a first thresholdvalue.

In this application, including the definitions below, the term“controller” may be replaced with the term “circuit.” The term“controller” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The controller(s)/control system may include one or more interfacecircuits. In some examples, the interface circuit(s) may implement wiredor wireless interfaces that connect to a local area network (LAN) or awireless personal area network (WPAN). Examples of a LAN are Instituteof Electrical and Electronics Engineers (IEEE) Standard 802.11-2016(also known as the WIFI wireless networking standard) and IEEE Standard802.3-2015 (also known as the ETHERNET wired networking standard).Examples of a WPAN are the BLUETOOTH wireless networking standard fromthe Bluetooth Special Interest Group and IEEE Standard 802.15.4.

The controller may communicate with other controllers using theinterface circuit(s). Although the controller may be depicted in thepresent disclosure as logically communicating directly with othercontrollers, in various configurations the controller may actuallycommunicate via a communications system. The communications systemincludes physical or virtual networking equipment such as hubs,switches, routers, and gateways. In some configurations, thecommunications system connects to or traverses a wide area network (WAN)such as the Internet. For example, the communications system may includemultiple LANs connected to each other over the Internet orpoint-to-point leased lines using technologies including MultiprotocolLabel Switching (MPLS) and virtual private networks (VPNs).

In various configurations, the functionality of the controller may bedistributed among multiple controllers that are connected via thecommunications system. For example, multiple controllers may implementthe same functionality distributed by a load balancing system. In afurther example, the functionality of the controller may be splitbetween a server (also known as remote, or cloud) controller and aclient (or, user) controller.

Some or all hardware features of a controller may be defined using alanguage for hardware description, such as IEEE Standard 1364-2005(commonly called “Verilog”) and IEEE Standard 10182-2008 (commonlycalled “VHDL”). The hardware description language may be used tomanufacture or program a hardware circuit. In some configurations, someor all features of a controller may be defined by a language, such asIEEE 1666-2005 (commonly called “SystemC”), that encompasses both code,as described below, and hardware description.

The various controller programs may be stored on a memory circuit. Theterm memory circuit is a subset of the term computer-readable medium.The term computer-readable medium, as used herein, does not encompasstransitory electrical or electromagnetic signals propagating through amedium (such as on a carrier wave); the term computer-readable mediummay therefore be considered tangible and non-transitory. Non-limitingexamples of a non-transitory computer-readable medium are nonvolatilememory circuits (such as a flash memory circuit, an erasableprogrammable read-only memory circuit, or a mask read-only memorycircuit), volatile memory circuits (such as a static random accessmemory circuit or a dynamic random access memory circuit), magneticstorage media (such as an analog or digital magnetic tape or a hard diskdrive), and optical storage media (such as a CD, a DVD, or a Blu-rayDisc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks andflowchart elements described above serve as software specifications,which can be translated into the computer programs by the routine workof a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory computer-readable medium. Thecomputer programs may also include or rely on stored data. The computerprograms may encompass a basic input or output system (BIOS) thatinteracts with hardware of the special purpose computer, device driversthat interact with particular devices of the special purpose computer,one or more operating systems, user applications, background services,background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation), (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, JavaScript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SENSORLINK, and Python®.

Clause I. A method of controlling a visual indicia of a hand-heldrobotic system for use with a saw blade, the robotic system including alocalizer, and a hand-held instrument having a hand-held portion to beheld by a user and a blade support movably coupled to the hand-heldportion to support the saw blade, an actuator assembly operativelyinterconnecting the blade support and the hand-held portion, theactuator assembly including a plurality of actuators, the blade supportincluding a saw drive motor, the method comprising the steps of:determining a position or orientation of the hand-held portion in afirst degree of freedom in a known coordinate system; determining arange of motion of the tool support in a second degree of freedom basedon the position or orientation of the hand-held portion in the firstdegree of freedom; determining a position and/or orientation of thehand-held portion in the second degree of freedom in the knowncoordinate system; and controlling the visual indicator based on theposition and/or orientation of the hand-held portion and the range ofmotion in the second degree of freedom.

Clause II. A hand-held robotic system for use with a tool, the systemcomprising: an instrument comprising; a hand-held portion to be held bya user and a tool support coupled to the hand-held portion, the toolsupport comprising a tool drive motor to drive motion of the tool; andan actuator assembly operatively interconnecting the tool support andthe hand-held portion to move the tool support to move the tool in aplurality of degrees of freedom relative to the hand-held portion toalign the tool, the actuator assembly including a plurality ofactuators; a visual indicator to guide the user; a control systemcoupled to the plurality of actuators, the control system configured to:determine a position and/or orientation of the hand-held portion in afirst degree of freedom and a second degree of freedom in a knowncoordinate system; and control the visual indicator based on theposition and/or orientation of the hand-held portion in the first andsecond degrees of freedom and a range of motion of the tool supportrelative to the hand-held portion in the first and second degrees offreedom.

Clause III. A method of controlling a visual indicia of a hand-heldrobotic system for use with a saw blade, the robotic system including alocalizer, and a hand-held instrument having a hand-held portion to beheld by a user and a blade support movably coupled to the hand-heldportion to support the saw blade, an actuator assembly operativelyinterconnecting the blade support and the hand-held portion, theactuator assembly including a plurality of actuators, the blade supportincluding a saw drive motor, the method comprising the steps of:determining a first pose of the hand-held portion in a known coordinatesystem; determining a first range of motion in a first degree of freedombased on the first pose; determining a second pose of the hand-heldportion in the known coordinate system; determining a second range ofmotion in the first degree of freedom based on the second pose, whereinthe first and second range of motion are different and the first andsecond poses are different;

determining a first position and/or orientation of the handheld portionbased on the first pose in the first degree of freedom and control thevisual indicator based on the first position and/or orientation and thefirst range of motion; and determining a second position and/ororientation of the handheld portion based on the second pose in thefirst degree of and control the visual indicator based on secondposition and/or orientation and the second range of motion.

Clause IV. A hand-held robotic system for use with a surgical tool, thesystem comprising: an instrument comprising; a hand-held portion to beheld by a user and a tool support coupled to the hand-held portion, thetool support comprising a tool drive motor to drive motion of the tool;and an actuator assembly operatively interconnecting the tool supportand the hand-held portion to move the tool support to move the tool in aplurality of degrees of freedom relative to the hand-held portion, theactuator assembly including a plurality of actuators; a visual indicatorto guide the user where to place the hand-held portion; a control systemcoupled to the plurality of actuators and the visual indicator, thecontrol system being configured to: determine a position and/ororientation of the tool support in a first degree of freedom in a knowncoordinate system; determine a range of motion of the tool support in asecond degree of freedom based on the position and/or orientation of thetool support and/or the hand-held portion in the first degree offreedom; determine a position and/or orientation of the tool supportand/or the hand-held portion in the second degree of freedom in theknown coordinate system; and control the visual indicator based on theposition and/or orientation of the hand-held portion and/or the toolsupport and the range of motion in the second degree of freedom.

Clause V. A hand-held robotic system for use with a surgical tool, thesystem comprising: an instrument comprising; a hand-held portion to beheld by a user and a tool support coupled to the hand-held portion, thetool support comprising a tool drive motor to drive motion of the tool;and an actuator assembly operatively interconnecting the tool supportand the hand-held portion to move the tool support to move the tool in aplurality of degrees of freedom relative to the hand-held portion, theactuator assembly including a plurality of actuators; a visual indicatorto guide the user where to place the hand-held portion; a control systemcoupled to the plurality of actuators and the visual indicator, thecontrol system being configured to: determine a first pose of the toolsupport in a known coordinate system; determine a first range of motionin a first degree of freedom based on the first pose; determine a secondpose of the tool support in the known coordinate system; determine asecond range of motion in the first degree of freedom based on thesecond pose, wherein the first and second range of motion are differentand the first and second poses are different; determine a first positionand/or orientation of the tool support based on the first pose in thefirst degree of freedom and control the visual indicator based on thefirst position and/or orientation and the first range of motion; anddetermine a second position and/or orientation of the tool support basedon the second pose in the first degree of freedom and control the visualindicator based on second position and/or orientation and the secondrange of motion.

Throughout this disclosure, certain indicia are described withparticular degrees of freedom—e.g., the pitch-roll indicia. It should beappreciated than any of the indicia described throughout could be usedto indicate the position and/or orientation in other degrees of freedomin a similar way, such as yaw, x-axis translation, or y-axistranslation. It may be useful to convey the position and/or orientationof these other degrees of freedom depending on the actuator assemblyused and the degrees of freedom available for movement of the toolrelative to the hand-held portion

Any of the control systems claimed herein may also feature one or moreof the features described below. The control system may be furtherconfigured to determine, in a known coordinate system, a pose of the sawblade, a pose of the hand-held portion, a target pose of the saw blade,and a boundary, and control the plurality of actuators to align the sawblade in the plurality of controlled degrees of freedom based on thepose of the hand-held portion and the target pose of the saw blade. Thetarget pose may be a target plane defined in at least three degrees offreedom. The boundary may be a boundary mesh, wherein controlling thesaw drive motor comprises controlling a motor parameter of the saw drivemotor at a first value and a second value, wherein the first value isdifferent than the second value, the controller operable to changeoperation from the first value to the second value based on the boundarymesh and based on the pose of the saw blade. The motor parameter may beselected from a group comprising speed, torque, current, acceleration,or combinations thereof. The control system determining a distanceparameter with respect a portion of the saw blade and the boundary,wherein controlling the saw drive motor is based on the distanceparameter. The control system may be configured to determine a positionof each of the actuators of the plurality of actuators, and determinethe pose of the hand-held portion based on the pose of the saw blade andthe position of each of the actuators of the plurality of actuators. Thecontrol system may configured to determine a pose of a tracker coupledto the blade support in the known coordinate system, and determine thepose of the saw blade based on the pose of the tracker coupled to theblade support in the known coordinate system. The control system mayalso be configured to determine a pose of a tracker coupled to thehand-held portion in the known coordinate system; and determine the poseof the hand-held portion based on the pose of the tracker coupled to thehand-held portion in the known coordinate system.

1. A hand-held robotic system for use with a surgical tool, the systemcomprising: an instrument comprising; a hand-held portion to be held bya user and a tool support coupled to the hand-held portion, the toolsupport comprising a tool drive motor to drive motion of the surgicaltool; and an actuator assembly operatively interconnecting the toolsupport and the hand-held portion to move the tool support to move thesurgical tool in a plurality of degrees of freedom relative to thehand-held portion, the actuator assembly including a plurality ofactuators; a visual indicator to guide the user where to place thehand-held portion; a control system coupled to the plurality ofactuators and the visual indicator, the control system being configuredto: determine a position, orientation, or combinations thereof, of thehand-held portion in a first degree of freedom in a known coordinatesystem; determine a range of motion of the tool support in a seconddegree of freedom based on the position or orientation of the hand-heldportion in the first degree of freedom; determine a position ororientation of the hand-held portion in the second degree of freedom inthe known coordinate system; and control the visual indicator based onthe position or orientation of the hand-held portion and the range ofmotion in the second degree of freedom.
 2. The hand-held robotic systemof claim 1, wherein the control system is further configured todetermine a range of motion of the tool support in a third degree offreedom based on the position or orientation of the hand-held portion ina first degree of freedom, determine a position or orientation of thehand-held portion in the third degree of freedom in the known coordinatesystem, and control the visual indicator based on the position ororientation of the hand-held portion and the range of motion in thesecond degree of freedom and based on the position or orientation of thehand-held portion and the range of motion in the third degree offreedom.
 3. The hand-held robotic system of claim 2, wherein the controlsystem is further configured to determine the range of motion of thetool support in the second degree of freedom based on the position ofthe hand-held portion in the first degree of freedom and based on aCartesian model representing a three-dimensional workspace of the toolsupport relative to the hand-held portion.
 4. The hand-held roboticsystem of claim 3, wherein the model is defined a plurality of rollvalues, pitch values, and elevation values.
 5. The hand-held roboticsystem of claim 3, wherein the model representing the three-dimensionalworkspace of the tool support is derived from empirical data.
 6. Thehand-held robotic system of claim 1, wherein the control system isconfigured to determine a pose of the hand-held portion in the knowncoordinate system, and the control system is configured to compute theposition of the hand-held portion in the first degree of freedom and theposition or orientation of the hand-held portion in the second degree offreedom based on the pose of the hand-held portion.
 7. The hand-heldrobotic system of claim 6, wherein the pose of the hand-held portion isa commanded pose, a simulated commanded pose, a measured pose, aprevious commanded pose, a previous measured pose, or combinationsthereof.
 8. The hand-held robotic system of claim 7, wherein the pose ofthe hand-held portion is a commanded pose, wherein the surgical tool isa saw blade, the tool support is defined as a blade support, and the sawblade is coupled to the blade support, wherein the commanded pose of thehand-held portion is a relationship between the saw blade and thehand-held portion.
 9. The hand-held robotic system of claim 3, whereinthe control system is further configured to determine an actualdeviation vector in a polar coordinate system based on the orientationof the hand-held portion in the second degree of freedom and theorientation of the hand-held portion in the third degree of freedom, theactual deviation vector having a magnitude and a direction, and whereinthe control system is configured to control the visual indicator basedon the magnitude of the actual deviation vector, the direction of theactual deviation vector, or combinations thereof.
 10. The hand-heldrobotic system of claim 9, wherein the Cartesian model includes aplurality of two-dimensional regions, each region surrounding its ownorigin, the actual deviation vector extending from the origin of atleast one of the plurality of two-dimensional regions to a point definedin a polar coordinate system by the orientation of the hand-held portionin the second degree of freedom and the orientation of the hand-heldportion in a third degree of freedom.
 11. The hand-held robotic systemof claim 10, wherein each two-dimensional region is defined by pluralityof roll values and a plurality of pitch values.
 12. The hand-heldrobotic system of claim 11, wherein the control system is furtherconfigured to determine a range of motion vector in the polar coordinatesystem based on the position of the hand-held portion in the firstdegree of freedom, the range of motion vector having a magnitude, therange of motion vector extending from the origin of at least one of theplurality of two-dimensional regions to a boundary points of thetwo-dimensional region, wherein the control system is configured tocontrol the visual indicator based on the magnitude of the actualdeviation vector, the magnitude of the range of motion vector, thedirection of the actual deviation vector combinations thereof.
 13. Thehand-held robotic system of claim 12, wherein the direction of theactual deviation vector and the direction of the range of motion vectorare equal to one another, and the origin of the actual deviation vectoris the same as the origin of the range of motion vector.
 14. Thehand-held robotic system of claim 12, wherein the control system isconfigured to control the visual indicator based on the magnitude of theactual deviation vector and the magnitude of the range of motion vector.15. The hand-held robotic system of claim 12, wherein the first degreeof freedom is elevation, and the control system is configured todetermine a boundary point of the two-dimensional region based on theposition of the hand-held portion in the first degree of freedom. 16.The hand-held robotic system of claim 15, wherein the control system isconfigured to determine the magnitude of the range of motion vectorbased on a pair of coordinates defining the boundary point of thetwo-dimensional region.
 17. (canceled)
 18. The hand-held robotic systemof claim 16, wherein the two-dimensional region is asymmetrical aboutthe origin. 19-49. (canceled)
 50. The hand-held robotic system of any ofclaim 1, wherein the visual indicator is a display screen separate fromthe instrument.
 51. The hand-held robotic system of claim 50, whereinthe display screen is coupled to a navigation cart.
 52. A hand-heldrobotic system for use with a surgical tool, the system comprising: aninstrument comprising; a hand-held portion to be held by a user and atool support coupled to the hand-held portion, the tool supportcomprising a tool drive motor to drive motion of the surgical tool; andan actuator assembly operatively interconnecting the tool support andthe hand-held portion to move the tool support to move the tool in aplurality of degrees of freedom relative to the hand-held portion, theactuator assembly including a plurality of actuators; a visual indicatorto guide the user where to place the hand-held portion; and a controlsystem coupled to the plurality of actuators and the visual indicator,the control system being configured to: determine a first pose of thehand-held portion in a known coordinate system; determine a first rangeof motion in a first degree of freedom based on a component of the firstpose; determine a second pose of the hand-held portion in the knowncoordinate system; determine a second range of motion in the firstdegree of freedom based on a component of the second pose, wherein thefirst range of motion and the second range of motion are different andthe first pose and the second pose are different; determine a firstposition or orientation of the hand-held portion based on the first posein the first degree of freedom and control the visual indicator based onthe first position or orientation and the first range of motion; anddetermine a second position or orientation of the hand-held portionbased on the second pose in the first degree of freedom and control thevisual indicator based on second position or orientation and the secondrange of motion. 53-62. (canceled)
 63. A method of controlling a visualindicia of a hand-held robotic system for use with a saw blade, therobotic system including a localizer, and a hand-held instrument havinga hand-held portion to be held by a user and a blade support movablycoupled to the hand-held portion to support the saw blade, an actuatorassembly operatively interconnecting the blade support and the hand-heldportion, the actuator assembly including a plurality of actuators, theblade support including a saw drive motor, the method comprising thesteps of: determining a position or orientation of the hand-held portionin a first degree of freedom in a known coordinate system; determining arange of motion of the blade support in a second degree of freedom basedon the position or orientation of the hand-held portion in the firstdegree of freedom; determining a position and/or orientation of thehand-held portion in the second degree of freedom in the knowncoordinate system; and controlling the visual indicator based on theposition and/or orientation of the hand-held portion and the range ofmotion in the second degree of freedom.